You can try one of the phones that are supported by Ubuntu Touch. I don't know how good it runs but there are several cheap (= old) phones on the list.
Pine hides their hobby-grade hardware behind in-development software. I owned both a PBP and PPP and much as I'd like to say otherwise, really can't say anything to recommend either.
Chiming in to say that my Fairphone 4 worked well with Ubuntu Touch, though I have since come to the conclusion that Waydroid doesn't really work for my usage due to many social apps not integrating well with notifications, as well as missing AGPS support, so I am back on Android with CalyxOS. If you find that GNU/Linux is not daily-driveable for you, I can definitely recommend that.