iodéOS (which is based on LineageOS 18.1) is available for FP4 : Installation - iodé
and /e/ OS (also based on LineageOS) is also available for FP4: Info about Fairphone FP4 - FP4
iodéOS (based on LineageOS 19) and CalyxOS are available for testing. However, I would not yet use these for an FP4 as a daily driver…
Since you are coming from FPOpenOS, iodéOS might suit your needs best.