I'd say the waterline of mobile Linux "seriousness" is whether a device has a bootable mainline kernel build. Once SoC support lands in the kernel, it becomes a problem for a lot of people on high salaries (including some at Qualcomm). And hardware support doesn't get dropped from the kernel overnight. For everything above, in userspace, you don't need a deal with OEMs or their blessing to make things work. It's a pretty generic stack: Alpine, systemd, familiar WMs/DEs.

But yeah, I hope to see more deals like the recent Motorola-GrapheneOS announcement in the future.

I highly recommend keeping an eye on postmarketOS blog. [1] It's a fun reading, and development's been really rapid lately.

What stopped me from full migration to pmOS the last time I tried it about a year ago was poor support of Magisk and Xposed in Waydroid, two things I can't imagine using Android apps without.

But! With some tricks you can get pmOS dualboot on OP6. [2] Haven't tried it, but looks amazing.

I think with the current direction and velocity, pmOS is going to get really close to Android in usability on supported hardware in the next couple of years. Except for power saving parity that never gonna happen.

[1] https://postmarketos.org/blog/

[2] https://wiki.postmarketos.org/wiki/OnePlus_6_(oneplus-enchil...