That's one of the issues with Svelte. It's a newcomer so the ecosystem is minuscule.

Personally I'm happy using Bulma with Svelte. I find most UI libraries tend to add too much bloat so I'd rather have something that only adds configurable CSS and just add as much JS as I need/want.

I used Vue+Vuetify some years ago. I wasn't very happy with it, but I agree Svelte needs something similar.

There are a couple of projects out there that add Svelte components for Bootstrap, Material, or IBM Carbon you could check.

https://sveltematerialui.com/

https://github.com/bestguy/sveltestrap

https://github.com/carbon-design-system/carbon-components-sv...

There are also a couple of projects about headless (no CSS) components for Svelte although I only seem to be able to find this one (not public yet)

https://svelteui.com/