I've been learning about the fascinating hobby of amateur radio: https://youtu.be/ysOq6ywTSzU
It reminds me of chat roulette, except all the users have a license and many of them build their own equipment!
Related Posts
Learning software development through playing and contributing to a MUD: https://tashian.com/articles/how-i-learned-to-program/
For hobby projects, I really like software where I can do small features or tweaks. Sometimes I don't have time for anything more substantial.
Website projects are great for this. Are there other areas?
Exploring design ideas using AI as a learning assistant, for creative exploration: https://andymatuschak.org/hmwl/