I help maintain Lit[1], which I consider a very standards-first non-framework.
With Lit you can build full apps with standard and plain JS, CSS, and HTML; standard web components; and no build tools.
I don't immediately see how this is any more standards-first, especially when it mentions Markdown, tooling, and a CLI. I don't actually really see what exactly this even is from this landing page. It would help to show something up front.
[1]: https://lit.dev
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