I know this isn't exactly the answer to your question, but it's sorta adjacent and might be useful.

Pixel devices can run a number of Roms that go much longer than Google's support period (DivestOS, PostMarketOS, Lineage, etc). Older models can probably be found on sale from Google for ~$200 occasionally or even cheaper used, and with Lineage offer a really long support period on an OS that resembles AOSP with or without G Services.

For anyone looking at budget android phones, probably the most important thing is to look at the CPU on gsmarena (or elsewhere) and make sure it has at least 2 a7N cores (the higher the N, the better, eg. a72<a78<a720), because android OEMs are still selling phones with 8 a53 (or a55) cores which are unusably slow (8x a53 cpus were terrible a decade ago, and they're even worse now). For qualcomm cpus you might have to check the wikipedia article [1] to figure out what the kryo cores actually correspond to.

[1] https://en.wikipedia.org/wiki/Kryo

I have a hard time figuring this out too. I have resorted to looking at benchmark scores for comparing mobile CPUs.

fairphone? The last one will have 8y + it's repairable. In terms of performance/camera quality it's far from apple/top snapdragon but still