There are several Linux phone projects being worked on right now. Not quite ready for the average user, but the PinePhone [1] is more than capable of making calls right now and is very affordable.
I was miserable with my PinePhone until I found out about https://github.com/dreemurrs-embedded/Pine64-Arch - this is an Arch-based distro that works very well, ime. Previous attempts results in glacial response times, sub-day idle battery drain, broken software updates, and overheating.
Mine was the UBPorts edition but I believe the latest shipped phone is Manjaro based. I was planning to try that as well at some point but the current version I have makes me happy enough to not want to experiment anymore :) . Edit0: s/release/shipped phone/ .
I've been quite happy with a F(x)Tec Pro¹ running Sailfish OS. It's a full Linux environment, and it's the best hardware keyboard I've used on a phone since the Nokia N900.
[1] https://www.pine64.org/pinephone/