Okay I know this is gonna sound rude but who in the world would want form controls that behave this way?
You've built something really great here, your grasp of web components is incredibly strong, and the way you use TypeScript is very light handed in a way that made the code just a delight to read through, in a way I've not had in many years. It's been a while since I looked at a new library's codebase and learned something new, so thank you for that!
This may sound silly, but I think you've laid the foundation here for the next Bootstrap / MUI. It just needs more expandability and distribution options.