Personally if it's a disposable old phone i'd at least try flashing divestos for h811 or h815 and see how it runs (seems the difference between 810, 811, 815 is just original carriers vs international variant).

Then again it depends how willing you are to tinker with trial and error.

For a pixel, can try paying attention when they announce or release the 8A, the 6s and 7s might go on sale (especially 6a 7a).

I'll let you know if I sell my 6a :P