From Avaya,
[highlight #FCE94F]Thank you for your time on call.
As you are aware Proxmox is a full virtualization platform and IP Office does not support the full virtualization therefore HyperV and ESXI is supported. However, Proxmox have the ability to restore VMs from ESXI backups and working further as a Proxmox VM, but as I mentioned this was never tested with Proxmox therefore, not supported. Good stuff to be honest but officially not supported. What I can advise is to try to import the esxi IPO backup to Proxmox and make sure in that the VM details are the same as it was on EXSi.
The ability to import esxi backup to Proxmox is available from Proxmox version 8.2.
Customer can use it, but risk is their own if it causes any degradation or unexpected behavior of IP Office.
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They didn't answer my original question though, which is whether or not they have future plans to support it considering the VMware situation.