I have a working (and not vibe coded) implementation of a "browser engine for apps": https://github.com/DioxusLabs/blitz
So far it's only HTML/CSS (and we have our Rust-based framework to write the apps in). But it has been designed for fast incremental rendering, so it could be extended with JavaScript support quite easily.
that looks very interesting. if it's targeting the electron/sciter market I would encourage you to put the binary size and memory footprint in the readme so people can see where it lies on that spectrum - it's one of my top priorities when evaluating a desktop app library.