

You could license it under the (A)GPL, charge for downloads in the Play store or for compiled binaries on ur website and ask for donations on F-Droid.
You could even do a freemium version where some features are locked in the binaries you distribute and need a license from ur website or smth (for those who don’t want to use Google Play). (iirc SD Maid 2/SE does this)
Someone else could just compile the app themselves, unlock all premium features and distribute it to play store without violating the license?
The newer Android versions aren’t that much more bloated. Sure. If you compare Android KitKat with Android 14 it is gonna be a bit more demanding probably especially on graphics, but overall there were a lot of improvements to the battery usage and memory management over the years and I have an experience of newer Android versions running better than the older ones. You can have a 6 years old phone that will run the newest Android version just fine because you flashed it with a custom ROM.
When we get to the manufacturer’s custom Android skins… Well that’s a different story. Most of them are gonna be more or less bloated than stock Android, but this is a problem of manufacturers and the fact that mobile OS market and ecosystem is so much locked down compared to desktop, which makes it harder to remove manufacturer’s bloat from your OS, install different ROMs and tinker with it, rather than Android being bloated as an OS.