Though I got some partial answers, people did not seem to get the full scope of what I was asking for and why.
The question already got several downvotes, but here I will share what I did so far, and may update if new insights pop up, or if I run into things that I wish I had done. Hopefully some people still see the benefit in the answer, if not in the question.
Wrapping things up that matter from the employers perspective
As numerous answers pointed out, you pretty much just need to do what is asked to cover your bases in this section.
In case your employer is on good terms but not able to explain well what he needs, the usual suspects are:
- Transfer knowledge on critical activities
- Transfer critical (information) assets so they may not get deleted together with your account. (Some things may get solved automatically, but if you have some important attachments in your mail they will almost certainly get lost if you do nothing)
- Return items that must be returned, typically you don't need to take the initiative surrounding your monitor/chair but be aware that it is very unlikely that a laptop or other data carrier does not need to be returned. If you don't want to think about your old job after the last working day, consider being proactive. (Specially if you end your employment with vacation, the communication may reach you rather late).
Wrapping things up that matter for myself as well as the employer
Perhaps some employers have fully ripened runbooks but here are some critical points:
- Align on a final working day (Not to be confused with the final contract date, keep in mind that in many countries it is actually a joint decision how many vacation days you will be taking vs having paid out.) Also keep in mind that if there is no clear policy regarding paying out surplus days, you should negotiate this before it is too late to take them.
- Align on communication to stakeholders (It is not up to you to communicate to colleagues or customers if the manager is against it, but assuming you care about your reputation and personal network you may want to push on your manager to go with your suggestions for how to handle things cleanly).
- Make sure NOT to bring corporate data with you. Perhaps you are using your private phone for work email? Then certainly remove the account on your last working day.
- Turn on your Out of Office, it may take a while for your mail to be closed properly and people seeing their mails unanswered will reflect poorly on both the company and you personally.
Wrapping things up that matter mostly for myself
- Make sure not to leave personal information. Are all files in the google drive automatically transferred to your manager upon departure? Then make sure to remove everything that he should not receive. Depending on how you used your laptop it may also have private passwords and such stored on it, to be safe it is probably best to wipe the device completely. (You don't want to find someone else using your Stack Exchange account...)
- Document agreements: For example, when giving notice to the employer I used my work email address, however to be safe it is good to put the private email on CC so it is documented externally that the notice was given on time.
- Handle internal stocks/options. You may want to sell these manually, though in practice stocks should be sold automatically if your account closes. I am not too sure about options, it is possible these may NOT get exercised automatically even if they are in the money, so certainly stay on top of this.
- Document entitlements
- Bonuses to be paid out
- Remaining vacation days to be paid out
- Remaining expenses to be settled
- Download important information
- First thing that comes to mind is the historical pay slips and annual statements
- Review (public) places where you used your work email, and update your email
- Communities (StackExchange, LinkedIn, Apache, Slack)
- Perhaps you used the work calendar for private appointments
- Things that need validations/other accounts (Cannot think of these now but feel I am forgetting some)