Low level contributions, maybe boring and repetitive work but is necessary and time consuming for a real developer (edited post to put this first).
I’m learning Python on Codecademy (so not a developer yet) and have completed their basic Python course as well as Intermediate, now I’m working on Advanced. Also I’ve completed about 6 others in the direction of Data Analysis that involve Pandas, Matplotlib, Seaborn, etc. my Codecademy page
After reading over the Home Assistant website, Github page (specifically ‘Contributing to Home Assistant’ and the FAQ pages) I got the impression I needed to ask on this Developer forum. Maybe there are some types of informal mentoring opportunities?