I'm using the ADC pins to make use of QMK's joystick feature. Or at least that is the plan.

It's interesting to see these rollers popping up some more, especially with two posts about them in such a short period of time(https://lemmy.world/post/4760068?scrollToComments=true). They're much better than the normal rotary encoders and I've enjoyed using mine a lot. Though sourcing them is unfortunately a bit tricky (and thus on the more expensive side).

I'm currently making a new board using the Nintendo Switch joysticks to replace them, I'm curious how the two compare.

I'm currently using a PinePhone Pro as my daily driver and if you want something to play around with that's definitely an option (though the PinePhone is probably a little more stable and less tinkery).

If you care less about it being a "free" phone built specifically for Linux and just want something that works, then rooting some older phone with good support will probably provide a better experience.