Docker uses a single Linux kernel for all containers. Docker containers are much lighter weight than VMs, since each VM must run a full kernel instance.
Yes, that's what I said. (although in a comment below this one. ;))
A container is much lighter weight than a VM, yes. (and so is a chroot)
But the MacOS userspace isn't running on the linux kernel, it's running on darwin. So, macos-in-docker would be an entire qemu installation in docker, with a macos image inside that.
EDIT:
Ahhh, because it doesn't make sense to run a full operating system in a container, only a single program, I'm guessing that what OP really wants is some way to dockerize a specific (or several) macos apps. To do so, you'd need a way to wrap the linux kernel do it can provide a darwin like api, as well as the same for any required libraries.
They made a MacOS to Linux translation (not virtualization) layer of sufficient quality that you an run a decent amount of (text only) native binaries.
A container is much lighter weight than a VM, yes. (and so is a chroot)
But the MacOS userspace isn't running on the linux kernel, it's running on darwin. So, macos-in-docker would be an entire qemu installation in docker, with a macos image inside that.
EDIT: Ahhh, because it doesn't make sense to run a full operating system in a container, only a single program, I'm guessing that what OP really wants is some way to dockerize a specific (or several) macos apps. To do so, you'd need a way to wrap the linux kernel do it can provide a darwin like api, as well as the same for any required libraries.
OP: You may find this project interesting: https://www.darlinghq.org/project-status/
They made a MacOS to Linux translation (not virtualization) layer of sufficient quality that you an run a decent amount of (text only) native binaries.