Name me a concrete phone model that has no significant compromises in hardware functionality. Maybe I missed those when I had a look into it.

The Postmarket wiki only shows a handful of devices where Call functionality is classified with "Yes", rather than "Partial" or even "No". Other than Pine Phone and Purism Librem that is only the Shift6mq from 2020 and four Xiaomi devices with the newest one being also from 2020, all of those have core functionality that does not fully work. Maybe that wiki is horrendously out of date but then this doesn't do good service to give newcomers a good idea where the project stands.

BTW: I am not saying btw that postmarket isn't interesting nonetheless to many people and a great project.