Select Halium devices do (e.g., FuriLabs FLX1, Jolla C2, Xiaomi Poco X3 NFC with Ubuntu Touch), but the issue is that it (AFAIU) also depends on whether the carrier agrees which IMHO gives these companies more power than they should be legally allowed to.

On mainline, there’s 81voltd now (said to work on Pixel 3a, OnePlus 6(T} etc): https://gitlab.postmarketos.org/modem/81voltd

First, I’d recommend going with the 6 (no T), which has a headphone jack, which can be helpful - and on these devices is your only option for wired headphones, as USB-C dongles don’t work yet.

Audio is unreliable, yes, not just for phone calls, also for things like podcast playback in my experience - at some point during use, my wired headphones just don’t show up anymore. A reboot fixes this, I still want to look at ‘milder fixes’ (unloading of kernel drivers, service restarts), but in months of daily driving I have not got around to this yet.

How can I daily a device with these audio issues? Well, I have always hated unscheduled calls, and force people to deal with it now. Also, if things don’t work: Reboot, call back, works.