The core of your question is how to determine what skills are important for a new career. Luckily, the answer to that remains the same, regardless of the career:
- Do your research. Look at job postings in your desired career path. Don't look just for jobs you actually want to apply to - look for jobs more senior (and less senior) as well. Write down a list of key words and requirements.
- Similarly, look through LinkedIn or other professional networking tools for people who already have those jobs. Find the profiles of people doing the work you want to do. Write down the skills those people have, and check their work histories and educational histories for any trends. See what their stories are.
- Look for online forums or discussion groups that focus specifically on the career path you're interested in. See what tools get mentioned most often.
- Perhaps most importantly, consider the nuanced differences in the positions and employees you're researching. People with the same title, but working in different environments, may have very different skill sets. You may think this will make your research less valuable, but in reality, it can be the most valuable part of your research, because it will ultimately be what helps you answer your question. More on this later.
It sounds like you've already done some of that baseline research, because you've arrived at a short list of technologies you're thinking of learning more about. But, before we actually address your specific problem of which tools to learn, you need to do some more thinking about what your ultimate goals are.
Ultimately, many problems can be solved with many tools, and there may be subtle differences between the different solutions. Some employers will care about these differences, others may only care about getting the work done. If you're starting from scratch, and will be looking for entry level jobs anyways, it may be just as valuable to show that you can pick a technology and learn it, versus trying to promote yourself as already being an expert in a specific technology. With this in mind, if you're in an interview, be thoughtful about talking through your problem solving approach and your approach to learning new things versus trying to focus on describing how you use or prefer specific tools.
In fact, focusing too hard on specific tools can cut both ways. If you happen to focus on a tool that a specific employer likes, it may be helpful to describe your expertise in it. But, focusing too much on a tool that an employer doesn't prefer can disqualify you. Since you've asked specifically about Excel, it's important to consider a few things: Programming in Excel can be incredibly powerful. You can solve many problems with it. In a general professional office environment, people who are highly skilled in Excel will be seen as Problem Solving Gods.
However, Excel doesn't scale well to true data science problem solving, and it usually isn't preferred as a primary tool among focused data science teams working on large and complex problems.
This brings us back to my bolded comment above. Once you have your baseline for skills, you can refine and focus in on the skills preferred for the type of environment you want to work in:
- If you want to be the lone data analyst at a community bank for instance, being an expert in Excel is probably a great choice. You'll be surrounded by Excel users every day, and you'll be working with problems that it's great at solving. Your boss in such an environment may not know anything about Python, but they will certainly recognize Excel.
- If you want to join a larger organization with a focused team, or one that is totally focused on data science, trying to show off your Excel skills during an interview may get you odd looks at best. But - talking about how you went to the useR 2020 conference and you really enjoyed the tutorial on integrating R with C++ will get you hired.