Sorry, i´m struggeling hard understanding your question.
Trying to get my head around this:
First: An appliance (as i understand it) is a virtual machine (VM) wich hosts a LAMP STack and a Nextlcoud on top of it, preconfigured to deploy and run with minimal configuration required.
NAS drives sometimes offer a nextcloud install, that is a snap or similar autodeployed on the hosthardware, in this case a NAS. The NAS is in this case not hosting a VM but rather hosting a webserver dircetly.
You can of course put the Virtual disks on a NAS, but i guess this is not what we are talking about here.
Where is your VPS and what product do you own. Please state what kind of access do you have to your vps.
Please clearify as much as possible.