I code everything in Python for GPT Actions. I saw and heard Actions/Plugin backend is in Nodejs. Naturally I don’t want to re-code it in TypeScript/Javascript. Is there a practical reason more people choose Nodejs than say Flask or FastAPI?
superior tooling, but that’s just an opinion. If you and your team are comfortable and competent shipping python, then it’s not a lesser option
FastAPI for the win.
It is easier to dev and update over time.
Flasks built in features work perfectly well, just build what you need and it’s done. Not everything has to be a generalised abstraction 
Yes, I will just go with FastAPI since the code base is very small at this point. Don’t need to over-complicated myself. If it grows, maybe I will see which one has better tooling or performance.