this is my main reason why I don’t want to switch to a new flagship from the Google pixel 4a. It’s not supported by google anymote, but it still runs smoothly with GrapheneOS (custom ROM), and I swapped the battery for a new one from iFixit and it just works! Maybe you can consider a Google Pixel 8a, at least it’s not as huge as other flagships
https://grapheneos.org/releases#sunfish