You can read most of the info on the VHD wiki page. You’ll find that 4 different interface cartridge models were produced but finding one will be tough (but patience and a bunch of cash will help).
Will any of the VHD interfaces work, or were there different standards?
All VHDpc interfaces should work OK with all VHDpc enabled players. This was the idea behind the VHDpc specification: you could control any VHDpc player from any VHDpc enabled computer/appliance. But, as the VHDpc interfaces are so rare, it's hard to determine how much the implementations are adherent to the original idea.
