Just at a cursory glance, this looks pretty verbose and clunky. Existing React ecosystem styling solutions are many, so it’s not immediately evident to me when you would accept the trade offs introduced by this tool over any existing ones that seem much nicer to not only integrate, but also have to work with day to day.
You'll be glad to hear that MUI is zeroing in (pun intended) on a zero runtime solution right now as an alternative to Emotion [0], although that GitHub issue doesn't capture just how far it has come. Expect more soon!