Also, https://postmarketos.org/ is a good project too.
And there's also a useful incremental path for evolution, that starts with a familiar GNU/Linux and moves gradually towards handheld tweaks (UI, power, devices, apps).
It's important to be upfront that PostmarketOS is not yet viable as a daily driver, or people will feel they wasted their time looking at it. What it really needs is programmers, like the earlier Linux ones, who will power through the pain of getting things working well, and stick with it for months, as a labor of love.