@charlie_root @3T @dcc @Decayable @Doll @Formerly_Trucks @Sui @p

The hardware is already there. UConsole is the one closest to it but it still needs a mic and speaker.
It's the software that is very lacking, especially the integration of the GSM module.
There is also a waveshare raspi hat with GSM.
Linux "phone" = raspi + waveshare GSM hat + touch screen + mic/speakers + battery.
Bonus for a RISC version with even better battery life.