Point being (again), definitions seem to differ, and what you call "full stack" is what I call "batteries-included framework". Full stack simply means (for me) that it gives you a way of building frontend and backend code, but implies nothing about what functionality is included in either part.

Nothing in "full-stack" requires having a validation library in order for it to be full-stack, that would more be leaning towards the "batteries included" approach to a framework instead of strictly being about "full-stack".

but you want to style your components yourself and not be constrained by existing design systems like Material UI