Thanks for sharing. I've been eyeing a fairphone 3+ for a while, and I remembered discussions around sailfish on the FP2, but it seems the FP3+ is not compatible. I'll have a look at the Sony Xperia.
For the FP2 and FP3 there are community ports. I think the FP3 port is in relatively good condition. Main drawback currently is that there is no Android layer available for community ports. There are plans at Jolla to bring Android support to community devices, but you can imagine that the expectations by users are hard to manage here :) Community ports are not supported by Jolla itself.