best advice I'd have for you is continuing with python is fine but
- find a good mentor
- read a lot of sourcecode (both good and bad), reason through stuff, try to understand the decisionmaking behind things
on the good, you could read code by people like glyph, hynek, projects like twisted. they have years of experience, high mark of quality, care for their work, and also do a lot of teaching
on the bad, you could read something like the code to home assistant (and/or esphome), or bits of calibre code (and calibre plugin code). I will say that these are not bad intentionally, but bad out of "someone inexperienced trying their best". it ends up creating a very particular kind of other thing.
you can, and should, learn from both
µPython is a bit of a special beast in that it's juuuust close enough (and handy enough) that it can trip you up, because there's some notable significant differences that if you spend all your effort in it first you might pick up bad habits that don't apply elsewhere (off the top of my head, some of the applicable: scoping, some arg-handling semantics, stack stuff)
other bit of advice: remember, it's all just code. especially when you deal with libraries, if some error is coming out of a thing your first instinct may be to try ask the internet but you could also dive into the library - follow the callpath, figure out what's what, see if you can figure the problem out yourself. it's often not too hard, and it gives you some good practice of code reading and reasoning
also from a number of devs who went borderline malicious compliance in "adopting tdd/testing" but didn't really grok the assignment