look for second hand thinkpads, models from x220 to x270 should fill all your needs. Screen size is 12". best you can get for 100-300$. Should come with 8gb of ram and decent CPU.
fastapi is valuable and useful tech. But it's also very over hyped with all the it's fanatics trying to throw it at every problem. Simple admin dashboard for few dozen users? FASTAPI. Backend for a mobile app? FASTAPI.
There is more useful and battle tested solutions out there for flask than fastapi (due to it's obvious time in the market, but still).
It's also interesting to check number of github issues for both frameworks (14 vs >1k).
I'm mainly backend guy (python), but used to do a bit of jQuery/bootstrap and basic js. Recently discovered quasar framework with vuejs and I'm amazed how productive it makes me.
https://viclabs.net
https://github.com/wiktorcie
My LinkedIn: https://www.linkedin.com/in/vic-cieslak/