I'm not sure if it would support inheriting from a custom store very well. It might get tricky with the templating. But the author of this seems to have done a good job of not ignoring inheritance.
Personally this library isn't to my taste - but I successfully use classes (without inheritance) along with reactivity primitives to create beautiful, tiny and high performance React applications
https://github.com/thalesfp/snapstate/blob/ba8a8d7ce25d6a4ef...
I'm not sure if it would support inheriting from a custom store very well. It might get tricky with the templating. But the author of this seems to have done a good job of not ignoring inheritance.