Seriously, try Svelte. See how its Stores API works. For bonus points, look at the Context API. Between Stores, Context, and what looks like plain ole JS in the component, state management is a solved problem. With all due respect, calling it a "monolith" out of hand just screams you haven't even looked at solutions and don't know what you're talking about.

SolidJS stores work the same.

In other words, this is basically a solved problem unless you live in the React ecosystem.