I mean, aside from /e/OS as a first-party option, there are also official Lineage builds[1]. And they're at least a target for PostmarketOS[2], even if that wiki doesn't actually describe something daily-driveable yet.
[1] https://forum.fairphone.com/t/official-lineageos-23-for-the-...
[2] https://wiki.postmarketos.org/wiki/Fairphone_(Gen._6)_(fairp...