That's really as far as they need to go; if the userland is compatible with Linux, it can use all of the work that KDE and other organizations have put into building mobile interfaces.

These projects have stuff that works, but the lack of firmware for chips that can connect to modern cell infrastructure means that they can't really create an appealing product. The OS layer is where all previous Linux phone efforts have failed, and I hope the FSF makes it farther than everyone else has.

> The OS layer is where all previous Linux phone efforts have failed

The OS layer is where the existing projects are thriving, with various distros and shells to choose from to match one's needs and tastes. It's the appropriate hardware that's in undersupply. I'm using a Librem 5, a 2019 design, and if I wanted to switch to something newer I can't because there's no viable upgrade path on the market. No other hardware vendor has invested significant resources into mobile GNU/Linux since then, everything else is either purely community-based or uses Halium.

Does webrender work with the Librem 5? Last time I checked it didn't-- Firefox disallowed it because the etnaviv driver didn't have all the features available needed to enable it. It appears there's been a lot of work on etnaviv recently but I don't know if it affects this issue.

etnaviv doesn't do GLES3 yet, so no, but the work to support it (mostly done by Christian Gmeiner) is ongoing and progressing. I'm using Epiphany though, it's pretty snappy these days and I make extensive use of its webapp feature. I don't even remember when was the last time I had to fallback to Firefox because of some incompatibility, but it did happen at least once.