I am the creator and maintainer of StreetComplete! StreetComplete is an app for Android with which it is super easy to contribute to the OpenStreetMap. Probably the easiest. Just yesterday, I released the new version v32 I was working on for… almost 5 months now, you may want to check it out, even (or especially?) if you don't know the app yet.
The app is, of course, licensed under the GPL 3.0 😉
I started the project about 5 years ago in my free time, later ramped it up to working on it several days a week. Last year, I was lucky to get some funding by the German Federal Ministry of Education and Research to work on it full time for some months. Otherwise, the project runs on individual donations via liberapay etc.
So, last year (but even up until ~now) was quite a ride, if you knew the app from before mid 2020, you should definitely check it out again – countless things changed, visuals too.Developer interest also spiked, in 2020/2021, so many new regular contributors appeared and added some cool things. For example, Florian Edelmann added a collaborative "team mode", i.e. map together with friends.
Anyway, ask me anything!