

I don’t care about which operating system, but my hobby projects have always included things that help myself. E.g.
- Software to collect/archive/analyse real life data (e.g. real estate data from various sources).
- Scripts to parse and structure data that I need e.g. for learning other things.
- Firmware for small embedded electronics.
- Home automation.
So my suggestion is to think of something that you need, but there isn’t a perfect solution yet. Although this advice comes from someone who has been working in software development for two decades now.
If you haven’t programmed before, think something very very small first.
The best learning material is the one you have motivation to follow through. Doesn’t matter if there exists better ones, if those will be left unused.