There is unfortunately not much I can do about this. Mozilla only has a "blacklist" interface for clearing localStorage and indexedDB. And without knowing which websites actually made use of one of them, it is impossible to "invert" this to be a whitelist.

So it's all or nothing. Either keep the feature of clearing localStorage and indexedDB disabled, but there is no other way to clear them on Android, or live with the fact that all will be cleared.

AND: Google is a bad example anyway. Google literally makes money by tracking you.