PostmarketOS has come a long way. In opposition to proprietary stuff they depend on people contributing which most people dont bother doing (translations, documentation, code).
That said, if you look here the majority of community supported devices lists calls as working.
To give this more perspective, I‘m working on a OnePlus6 with PostmarketOS at the moment and trying to make it userfriendly. Its a lot of work and in my case far too advanced for a regular user but contributing in general isnt ans the phones are developing.
The important part about postmarketOS is that you can finally own your device, unlike with android and ios and even after support ends unlike grapheneOS afaik. Obviously you still have proprietary blobs for modems and such but YOU can be the person that changes this.