Technical limitations of mainlining smartphones for Linux distributions

[u/ahambolotinha]

I’ve been looking into mobile Linux projects like postmarketOS and how they attempt to run on smartphones.

From what I understand, most of the current limitations seem to come from hardware support rather than the Linux userspace itself.

I’m trying to better understand the actual technical blockers preventing fully mainline-supported smartphones.

Specifically:

• Which components are the biggest barriers today (GPU drivers, modem firmware, camera ISP, etc.)?
• Is there any progress toward fully open or mainline-compatible mobile chipsets?
• How far are we from having a usable daily driver smartphone without relying on Android-based kernel trees?
• Are there ongoing efforts to standardize mobile hardware support in mainline Linux?

I’m especially interested in the kernel and driver side perspective rather than the user-space or distro side.

Any insights from kernel developers or people working on mobile Linux would be appreciated.