Dual sim
Do any combination of phones and OSes have support for desktop Linux apps, VoLTE, and dual-SIM?
I want to get away from Google. My current phone (Nokia G42) doesn't seem to have support for any OS except Android. My ideal setup would be a Fairphone 5 with Ubuntu Touch, but that doesn't seem to support dual-SIM.
The FLX1s meets those criteria. No direct experience as I too am searching for a linux phone, but this one is a lead contender.
FuriOS
ESIM work on Linux?
There is a new experimental app for writing on them (qualcomm chipsets only I think). But you can also continue using them after flashing a Linux OS, as long as you don't change them.
Maybe look into the Oneplus 6? It has a dual sim slot and can run Postmarketos, though I have no idea whether the software can handle dual sim and stuff like VoLTE probably won't work.