Maybe my response in this thread is of help here:
Whether Roon runs in a VM or on baremetal won’t change how much memory Roon needs. If you wanted to, you could try putting Roon in a container and thus save on total required RAM for a running system with Roon on it, but a VM has an entire OS running and thus the VM will be no different than the same OS running non-virtualized (pertaining to memory usage for a Roon Server).
So, if you have a server (VM or physical) with enough resources (RAM, CPU) for a Roon server fitting to your music library, you shall be happy.
How much RAM Roon needs, that depends, and it’s not the same thing as how much RAM the operating system (Linux or Windows) plus any other applications and processes running on that system need along with your Roon server => see the linked post above.