That does not seem to actually be "in a docker container"?<p>It is just using docker to run the VM software (qemu with kvm) and runs macOS in that VM.<p>It is conveniently packaged up, but the title is very, very misleading.
<a href="https://github.com/sickcodes/Docker-OSX">https://github.com/sickcodes/Docker-OSX</a> seems more established. I used it a while back when I was in a country where that was legal. These days I just use GitHub Actions instead.