There quite a few in javascript/browser world:
- Browser Houdini effort https://ishoudinireadyyet.com/
- Service workers https://jakearchibald.github.io/isserviceworkerready/
- Svelte 5 new version https://svelte-5-preview.vercel.app/status
- Turbo bundler rust rewrite https://areweturboyet.com/
And prob much more