As an owner of FP3+ (bought it around the end of 2023) i start feeling a bit outdated))) The current phone suits my needs, though - so not gonna dump it.)
The fp3+ actually has the audio jack (which i think i've used only a couple of times, tbf)) - but i'm mostly interested how/whether Fairphone can make feature back-compatible models and/or modules.
I'm guessing, keeping compatibility (between different models/generations) is not quite possible, though.
It has lasted two years so far and it is working without issues. Like I said, i'm not going to dump it just because a new model is released, and i keep using the FP3+.