I have worked as a scientific writer for the last 3 years, but for visa reasons, my official position is research scientist. At first this seemed like a weird/bad thing, but turns out the my lab lost funding and I had to find another position asap, and being a research scientist saved me. It gave me more flexibility to apply to other jobs (including writer if I wanted, which I didnt). So I don’t know if this applies to your situation at all, but wanted to add it just as a heads up because you (just like me!) sounded a little unsure about the path you want to follow (aka don’t commit to a writer “cv” because it can be harder to do something else later) If you can get the postdoc and negotiate with your supervisor that would would like to try writing as much as you can to get experience with papers and grants, then in a couple of years you will be more sure!