If that's your first target for removal, I'd wager a large amount of money that you're [unfamiliar](https://man.netbsd.org/compat_freebsd.8) with the NetBSD code base.
This is part of the contract all new committers are required to sign. Becoming a NetBSD committer requires membership of the NetBSD Foundation and there's an understanding that trust is expected.
The article is wrong, it has branding disabled (so it identifies as Nightly), but it's stable Firefox. And the linked article indicates that one compositor can be used.
All active Unix-like operating systems aim to implement the new interfaces as they're defined.