What do you even use your phone for nowadays? I barely have any apps in them. I just use Twitch, Youtube, browsers (for Hackernews) and Reddit. All of which is big enough that they are prolly the overlords in said walled-garden. Are there any niche apps that is _very_ useful and yet _very_ obscure?

https://github.com/streetcomplete/StreetComplete

The UX is good enough that my five year old can use it (with a little help to read the rarer, worried quests).

Seriously, check it out. It took contributing to OSM from "painful thing I do occasionally from a sense of duty" to "fun hobby I look forward to doing and sharing with my kids."