Compact Android phones are relatively rare, so start with the actual body dimensions and weight, not only screen size. Thin bezels mean a phone with a fairly large display can still be easier to carry than the diagonal suggests.
For long ownership, I would put the update policy near the top of the list. A compact phone often has less room for battery, so also check real endurance and charging speed carefully. Small size is not a good trade if you need to top up twice every day.
My ideal compact choice would combine manageable width, reliable one-handed use, strong main camera, several years of remaining security updates and enough storage for the full ownership period. If you share the maximum size you consider “compact,” the shortlist becomes much easier.