Well it worked on firefox before, but only on macOS:
https://www.youtube.com/watch?v=rDq1AN1kSn4
https://web.archive.org/web/20210331133857/https://developer...
> But kinda like Rust, it's a thing that spun out of Mozilla and has taken on a life of its own.
It could has been a feature that make firefox the browsers for developers, instead it's a new paid subscription dev product.