Reading the rust book is a great use of your time. Rawdogging is a good method if you’re just concerned with things you’re working on. You can also read documentation on different things that you may not be working on, but know is a gap in knowledge. For me that was the async and tokio books as async rust is a bitch.
A lot of rust libraries use the same approach by having some type of “book” for documentation. I treat them like normal reading, so I’ll be out and about or just sitting and I’ll pull one out and read it leisurely. It’s another way I’ve found to learn by osmosis. Doesn’t even have to be something I’m working on, just something interesting. It sounds like you’re doing what interests you, and that’s what’s important.
This sounds amazing! I will also put here there’s also chronometer that has a lot of the same functionality as fitnesspal but without the subscription, but you have to use an account.