Aren't you loosing a lot of the declarative features like signals or similar, when you do your projects without those frameworks?

(asking to learn)

Somewhat. I could still use framework agnostic state management libraries/patterns and most are (e.g. svelte signals, jotai, zustand, etc.).

I've even used Proxies directly to implement some reactivity before. However as for the "declarative" parts, I think it's just a little bit of a different way to work but you get used to it and imo it pays off. Knowing the web APIs should be a requirement anyway and it doesn't hurt to work with them directly as much as possible.