@linmob
Gurk is by far the most promising option I've seen so far, thanks for recommending.
It will lacks usability on mobile screens and seems to be link-only and not standalone, but since I don't plan to daily-drive ATM, it's not a problem.
@silmathoron I recently read that someone managed to pair Signal Desktop to Axolotl, so PinePhone only is not totally impossible.
I managed pair signal desktop with Axolotl on a Librem5. The most annoying part was the QR code that the desktop app generates that you need to put in Axolotl. But as long as you can convert the QR code content to text you can just copy paste it.
