> Not sure how well this would have fit into Firefox as a specific feature, given both the browser C++ runtime customizations and cloud wizardry needed to make this work.

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.