There is an old proverb that says, "A person who tells the truth should do so with one foot in the stirrups" - which is to say, you are right in thinking that simply sharing your honest perceptions and opinions can put you on the wrong end of a whole crowd of pitchforks, so you had better have an escape plan. This is, generally speaking, not a comfortable place to be. You do have a few options on how to proceed.
But first, you need to consider the core reality of what you would be trying to do. People who like their job as-is don't want it to change, and people who don't like their job won't automatically prefer the alternative you offer. Offering a different way - even if it were absolutely, objectively, vastly better than the status quo - is still highly likely to upset an awful lot of people.
Are you fine with that? If not, you should probably just parrot socially acceptable platitudes like about how you've been doing this a long time and just tried each day to be a little bit better, and luck helps a lot, and I couldn't do it without great teammates and managers, etc. They won't like that you aren't more helpful, but oh well, I guess you just don't have some secret recipe for success after all.
If you want to be be an agent of change, you will have to accept that this can backfire on you and make people upset, or even get you fired. Producing a radically new invention that the whole company adopts and turns out to be greatly successful can still end up badly for you personally, and you need to know that going in. We wouldn't have a saying about "don't shoot the messenger" if people did not, in fact, tend to want to shoot messengers. People are just like that, change is hard, and 9/10 change projects fail - just like how you've noticed most projects get thrown away, too!
If you want to proceed anyway, you have a few major options.
Option 1) Diplomatic Skills
There is a difference in speaking truths in a way people will not accept, and finding a way to say the truth in a way that people will tend to find acceptable. In general, when you want to change things, you need to find out common ground and existing pain, and start there. For instance, do your coworkers complain about all the wasted time and energy that is put into things that never go anywhere, help anyone, or seem to have any benefit at all? Do they publicly or privately grouse that most of what they do is BS? If so, you can start there, acknowledge/raise awareness of how many people feel this way, and then talk about how this can be addressed by being explicit about the fact that 9/10 projects are actually "throw-away prototypes" (the common industry term I'm familiar with).
I'm personally fond of analogy, so I like to point to sand mandalas:
The practitioners spend hours upon hours constructing individual grains of sand into works of beautiful, intricate art - and then ritually dismantle and discard them. It seems like such a waste! How can you spend so many hours on something, only to throw it away, to not even try to save it or use it for something for more than the day? You'd be wrong to think it is easy for them, just because they are monks - that's a big part of why they do it. Even the best of things play their part for only a little while, and then return to nothingness.
The problem is, of course, not all of your coworkers are the same, and even if you love this and find it very appealing and spiritual, some will find it deeply depressing, unacceptable, stupid, short-sighted, fatalistic, and a dozen other nasty words (some of which will be found in the comments section). Some may enjoy focusing on "quality" of what they do, even if it is absolutely worthless to anyone else; effectively their job is like painting model airplanes that they will store in a box and no one will ever look at. Its fun for them, and good for them for having something they enjoy. These people are not going to be pleased that you point out that most of their work doesn't benefit anyone else, or the company, or the customers, etc.
Diplomacy has its limits. You can get more allies with a well told story than without, and making a negative into a positive - its not a BS waste of time if it is an experiment we knew in advance might not turn out to be used! But if you think it'll make you a hero to everyone, oh you will be so disappointed. Politicians can be great at this, and you know how people think about them!
Option 2) Ask For More Than to Give Advice - Ask for an Experiment
This generally starts with humility, and you basically turn people's request to share your secret formula into the basis for a bigger request. You do things differently, you agree with them, but not only are you not sure that anyone else would benefit from working the way you do, but you aren't even sure if the ideas you have are even why you are so successful at what you do. But - you have some ideas. You couldn't even begin to suggest them normally - no, they are far too crazy! Forget the whole thing, never mind, you should just get back to work.
But, well, if they persist - propose an experiment you'd like to conduct. You'd have a small team of coworkers you select - a "tiger team" in business-speak - and you would need authority to decide to do things differently in terms of project management/structure. You can explain how you would go about it - insisting that everything be built as a throw-away prototype first, with your coworkers all ageing on your crazy ideas of building fast and hacky and only even try to fix it later if the project ends up really being wanted in the end, etc. The goal of the experiment is to determine if your methods really work for more than just you, and it will need a set amount of times/projects, and a preset review process.
If at the end of the time period (6 months, a year, whatever), it is agreed that this didn't work out, you just go back to doing your work as you have done it and everyone else goes back to doing things their own way. If it works, you then have a meeting on if you expand the team, try to make a second team, etc. Less risk for you, your bosses, your coworkers, etc.
And if they don't want to give you that kind of arrangement? Then they don't actually care about your opinion. They want cheap progress, they want a magic pill, and that doesn't work and you don't have it to offer. They may just want someone to blame when things go wrong, or any of a thousand other reasons. But the fact is, if they aren't willing to offer you more than the chance to share a few words of wisdom, they don't really value you enough to bother. Anything you say would be as "pearls before swine" - they don't actually care, they just wished everyone did as much work as you do, without having to any hard work to make that happen.
Option 3) Ask for Outside Help In Experiments/Change Management
Other people have ideas similar to yours, especially about throw-away prototyping, rapid application development, reducing work on things that aren't going to ship, etc. So if you don't want to be in charge of all this, suggest the possibility of consultants who seem to share your ideas and are happy to roll in, upset people, and roll out with only their paychecks if things turn sour. The upside here is - you get someone to blame, too. "Jeeze, what a bunch of frauds, glad you kicked those guys out - oh well, back to work."
The other upside is they may have more experience in how to manage process changes like this, it requires management to make the decisions to hire them and accept/reject their advice (management support is basically required for things like this to work), and other than having a few extra meetings you can mostly just go back to focusing on your work. You can still be blamed for the suggestion, and they might turn out to suggest the opposite of what you would have, but at least most people are usually happy to blame outside consultants (and management for hiring them) instead of you.
Option 0) Just Decline
I end this advice as I began it - you can just decline. What works for you, works for you; your coworkers won't like it, they'll probably refuse to do it and would likely screw it up anyway, everyone will look to blame you for absolutely any downside while refusing to credit you for upsides, so why exactly do you want to agree to carried up the volcano by the over-excited villagers just because they offer you a laurel?
In my personal experience, I found I loved research projects of this type, trying to discover better ways of doing things and sharing them with others, and I found out (mostly the hard way) that if your officially mandated job is not exactly this, it will usually go badly for you. You will be blamed for the bad, others will take credit for the good, any issue with your other work will be more strongly criticized and you will be accused of "losing focus on the job you were hired to do". In the end, what worked for me was taking my experience and switching to work in research and development, where this sort of thing is explicitly "your job". What I have seen working for others is some variation of the above options, none of which are easy.
I've only ever seen one other thing work, and that is when management - from the top down - was explicitly invested in growing and supporting an unusual culture of championing the testing and growing insights offered by workers. It's so unusual that someone will generally write a book about it.
Choose wisely, and good luck - you're going to need it either way!