No Linux OS currently supports many models of phones, and the ones it does support, it is still quite janky and not ready for a general audience (calling is often flakey, phone apps are pretty glitchy, etc). The best we can do at the moment is either donate toward those projects with either money or code (if someone is able to) to help get more hands on it to polish it up and expand support for more phones.

GrapheneOS is currently the only really polished privacy respecting mobile option that the average user can realistically adopt.