I've also reached a similar conclusion while building ZeeeroOS from scratch.
There's also Fat binaries(arch independent) that should be considered but no one does when building for Linux.
I think you misunderstood GP's request of "running macOS apps on Linux" so you swapped the host and guest OS, and then transposed the guest OS under "emulation"
This is a lie. Gatekeeper in no way limits the software you can run. It presents an easier experience to launch software downloaded from a browser if the developer chose to submit it to apple for a malware scan.