My FP4 has 3 years today (I wasn’t an “early adaptor“ 
).
First I used the Fairphone OS, later I switched to IodéOS, currently v6.14. I like having this de-googled Android, although I still use some Google apps, but not “all“.
The manual update to 7.4 is pending, since it’s not straight forward as usual (see Fairphone 4 update to iodéOS 7.4 - Installation Help - iodé community )