It’s great that smart people are working on this, but I don’t think we can expect hobbyists to make a useful OSS implementation of smartphones. Especially since there is so much dependence on the hardware. We either need a company that can throw some weight behind it, or just straight up governments that value it (e.g. from a sovereignty point of view).
The best thing to do is just start with whatever you already have. An old gaming rig, laptop or Raspberry Pi, doesn’t matter. Each will present some technical obstacle that you need to overcome (for example keeping the laptop going when the lid is closed). That’s part of learning.
Self-hosting is a hobby where we gradually learn more. Experimentation is just as important as reading the docs.
This is pretty much always the case when you start a new job. It takes time adjusting to the environment, the people and everything else. It’s going to get better, it always does.
However, skipping proper food and exercise is counter-productive, so do make an effort to cover those needs.