Hyper-V does function under the garb of 'Windows Hypervisor Platform' and 'Virtual Machine Platform' even under Windows 10 Home. I have it installed and it provides the virtualisation capabilities for Device Guard and Core Isolation/Memory Integrity.
Virtualbox from version 6 has been forced to fallback to Hyper-V when the latter is running, as it doesn't relinquish control to another virtualisation software.
So there is no reason why MS cannot implement Windows Sandbox even on Home since the underlying tech actually functions on all Windows editions, provided hardware support is there.