I'm not sure if I've entirely grokked the idea of components, but can't you define them server-side? So write them as some template magic that creates the "inner HTML". Then you just need some HTMX to enable using the component in a richer way.

It's not really Web Components as specified, but iirc those are generally pretty much JS-dependent? But hypermedia's reliance on server side rendering means that you can just move this logic to the server.