i'm using a fairphone 4, i'm pretty happy with it.
i like their goals of sustainability and repair friendly builds. i just got a security android update yesterday, although the one before was quite a few months ago, so it's not as frequently updated as it was in the first few years

Ive been disappointed with fairphone 5, OS updates were late and not in full. Other security risks like the original OS signed with android test keys. I see that you want to flash another OS on there so this isn't relevant for you, but I am a bit disappointed.

I have a few major gripes about the Fairphone 6 which otherwise looks like an awesome phone. It costs an extra $200 in the US. So it’s a midrange phone made out of plastic for $900. Really difficult to justify that unless you have a ton of disposable income. Then you can only use it on T-Mobile. While it’s awesome that parts are easily replaced, I wish there was a way to upgrade over time. I’d imagine those parts will cost more in the US as well.

They can ship it with e/os already installed, which is awesome.

I know someone with a fp4. It seemed like you could get 'more' phone for the same amount of money, at the time. But then again, i have a feeling that not all brands/models are supported in the same way that fairphone strives to.

USB 2, therefore no external monitor.
If they make 6+ (like there was 3+) with USB 3, then I will consider getting it.

I had a fairphone 2 years back. Had the battery replaced once, otherwise it worked fine. It was a bit clunky, a bit slow, the camera wasn't that great, it felt a bit out of date overall, but I'm not crazy about this sort of thing, I just need a basic smartphone. For me the environmental and fair trade aspect was the selling point, not the technical stats, so I can't really speak on that. It was .. a phone, lol. It worked fine. Friend of mine is using a newer one (not sure which one) and says they've done a good job to bring it up-to-date and especially make the battery last longer. I don't think they aim for super high perfomance cutting edge phones, so don't expect that. Oh, because you can take them apart, they are obviously not waterproof. Just something to know.

My only turn off is the lack of a tele-camera: I love the 4x (104mm eq.) on my Pixel 6 Pro and I don't think I can live without it.

I use iodé OS and I'm having a blast.

I heard Fairphone's voice to text function sends data to open AI with no option to opt out. Anyone know anythung about this?