Comment by seba_dos1

It's obvious, someone has tried it, it works and is commonly used on those more FLOSS-conscious and de-googled "ROMs" - it's called microG. It's not Play Services that are the limit, it's device attestation.

Same with the device proposed by the parent - I can plug my Librem 5 in to a display and keyboard and it runs a regular GNU/Linux distro while working well as a phone, without Halium or any other Android bits.

We had these things for many years now, just look around harder :)