I'm not one those (very admirable) people who build just to build, who make their own version of frogger or something. I need a problem to solve.
But making a program that would take the parameters of a physics problem and spit out all the other quantities or that formatted output the way my stats teacher wanted it was a huge timesaver and that motivated me.
I bounced off a python 2 tutorial and a C tutorial, but some random nobody's TI-BASIC tutorial that started really damn easy is how I became a Computer Scientist.
I eventually figured out python too!
I made my own game and got a little notoriety around the school for it.
Termux
pkg install python
python
print('hello')
ctrl+D
Haven't tried these, but have seen them recommended:Acode
Termux + neovim
Termux + code-server (vscode-like, accessed through phone browser at localhost)