If you're looking for a library to build components and apps with that does let you use plain JavaScript - to the degree that you can write working components in your devtools console - check out Lit: https://lit.dev/

For deep reactivity, we have add-on packages for signals, and we're aiming towards integration with the upcoming Signals TC39 proposal: https://lit.dev/blog/2024-10-08-signals/

Lit's used by pretty major apps like Photoshop, Reddit, Home Assistant, and The Internet Archive.