Here's how you build Redox from Mac in May 2025. It's so much easier to do it now than in ancient days.
The only problem you may encounter is packaging the build, since it requires FUSE and it's requires patching Mac kernel, which I don't want. I (trying) develop a way to avoid it by using Podman only for that.
I run with UTM on QEMU virtualization. It works for me.
This notes is WIP, see https://gist.github.com/willnode/a31a1265d955dbb914001aba8a576ad2 for Redox OS native bootstrapping