It will be deGoogled soon enough. The Fairphone 4 is supported across several deGoogled versions of Android including CalyxOS, iodéOS, LineageOS, DivestOS and /e/OS. The Fairphone 3 and even the 2 are also supported by some of those operating systems.
Lineage is the oldest one (Divest and /e/ are forks of it). Calyx has a focus on security and privacy (comes with a free VPN with no signup requires). Currzntly Calyx is based on Android 13, even on the Fairphone 4 which doesn't have it supportes. I son't know enough about iodé to comment about it though.
CalyxOS is the most advanced of those I mentioned. They have a monthly update schedule and a larger team. My favourite is iodéOS, though, because of the iodé ad and tracker blocker app which can be used simultaneously with a VPN.
No, I mean it runs system wide and can block ads and trackers from any application. There are definitely no ads in the OS lol
Normally these ad and tracker blocking apps are detected as a VPN by Android, which means you cannot use a real VPN at the same time. iode's blocker is unique in this area.
This one is degoogled and running e/OS/. I don't know anything about the company that offers it or their services, though. Seems like you can optionally set up the phone with a user account supplied by them in much the same way as you'd use a Google account on stock Android.