This... is actually pretty great to have. Very cool.
That said... It really just makes me bummed about the lack of good support for container and sandboxing technology on macOS. I know, totally different thing. But still, we'll probably never have a "native" Docker/Podman/etc. on macOS, and things like the Bazel or Nix sandbox are significantly less effective on macOS due to there just being less kernel APIs for isolating resources. e.g. There are no network namespaces. I get why, but it's surprising how limiting not having network namespaces is once you have used a platform that has an equivalent to this. For Nix it's really tricky since a lot of things need at least a working localhost inside the sandbox. I am sure increasing the surface area of XNU is not a serious consideration, for good reasons, but it's a bit of a shame.