In the Windows case, they can enforce your inability to install/enable Hyper-V on Windows Home through simple measures like protecting system files from modification.

But in the iPadOS case, the only way to really prevent you from running a macOS VM, is by preventing you from running any VM.

Due to the Turing-completeness of virtual machines, there's really no lesser measure they can take. You literally cannot create a piece of software that can run arbitrary VMs except for if the VM is semantically macOS. Whatever signal you would look for to blacklist macOS, an adversarial VM creator can mask by modifying the installation. (At an equilibrium point of such a game, the "adversarially-created macOS VM" would end up looking more like a Hackintosh rootfs than like a Mac rootfs — but it'd still look and feel and work like macOS, and that's all users would care about.)