OS update is less of a concern to me. If the phone is from a major company, there will be custom ROMs like the LineageOS sooner or later. It will last me a good while before becoming obsolete as long as the SOC is good enough.
Actually, come to think of it, I think Sony has been releasing 5" phones as the Xperia Ace series. They are budget phones that are only available in Japan. I heard the spec is not very good, so I didn't bother to get one.
Galaxy S21/22/23, Asus Zenfone 8/9 or Sony Xperia 10 or 5 Series
These are very good phones but they are not small enough for me.
The size of XZ2 compact is very nice but I hate the curved edges and back panel. I think XZ1 compact actually suits me better, but it is almost 6 years old now. I don't think I will be able to use it for long.
OS update is less of a concern to me. If the phone is from a major company, there will be custom ROMs like the LineageOS sooner or later. It will last me a good while before becoming obsolete as long as the SOC is good enough.