[Mashiro]

I was wondering if macOS was a supported operating system with the VPS Providers?

Most likely not. On request? Maybe a tiny chance but still most likely not.

I was wondering if MacOS Server was a supported operating system with the VPS Providers?

Absolutely impossible to highly unlikely.

I have ran macOS in a KVM environment before, but while reading the TOS for some of the hosts I did not see any thing regarding running a Headless Virtual Machine.

While that might be true you still should be very careful with running nested virtualization. I guess it be better to let the staff here ask on your behalf via support ticket (if possible here) if that is allowed.

Well, lowend market is always very iffy with almost everything non standard. If you were to buy a VPS with a provider like OVH, Hetzner or similar they wouldn't bother... unless you do something really massively dangerous (hacking, DDoS attacks, CP, everything absolutely illegal).