We're doing this exact thing. Our micro front ends are React components (most of them are actually now using hooks!). Our 2 deployed UIs are angular (1!!!) apps

We're doing this exact thing. Our micro front ends are React components (most of them are actually now using hooks!). Our 2 deployed UIs are angular (1!!!) apps. We use react2angular to slowly replace the angular app. The angular components are all Java backed using a poorly maintained swagger set up (and the swagger definitions don't match the actual services :( ). The new backend is all Graphql on top of typegraphql. The nice thing about typegraphq is how easily it converts our models into usable rest services, and allows us to create field resolvers, that basically extend other types and let us pull down additional concepts. Basically we let the front end then choose what it wants to pull down. It's very flexible, self documenting, and reduces the amount of boiler plate we had in in the Java layer a ton. One set of model objects (typeorm) that also have typegraphql decorators. Compared to Java that has models, swagger objects, converters (both ways)... Life before was literally a nitemare.