I recently bought the FP6 with android preinstalled and installed /e/os myself because it was cheaper that way. Installing the is is not difficult at all and there is a detailed guide availabe.
I'm pretty satisfied so far. I'm not missing any functionality except for the headphone jack, but I was willing to compromise on that. Sadly it's almost impossible to get a phone with headphone jack nowadays anyway.
I generally look for smaller phones with long battery life, and value durability and longevity over cutting edge features. In that regard, the phone is very good in my opinion. It's smaller that current flagship phones and over the holidays I even went a week without charging it, on day-to-day use I'm currently charging it every 2 to 3 days.
I can't speak about how repairable it is yet myself, but according to FP and ifixit repairs should be very easy for things like changing the battery and doable with some steady hands for more complex repairs. There are no glued down parts, everything is screwed down or clipped in and you can buy spare parts straight from the manufacturer.