Just check, my 2YO phone runs kernel 6.6, not latest but i think good enough for production.
Edited: I misunderstood what you mean, you were talking about the modem subsystem, sorry.
Edited: I misunderstood what you mean, you were talking about the modem subsystem, sorry.
https://www.telit.com/devices/fe990bxx/ - "High-performance quad-core CPU and Linux OpenWRT OS, ideal for router development without an external CPU"
Plenty of cellular modems run Linux.