If it scales and the proxmox team can grow their support organization, they’ll have a real shot at capturing significant vmware marketshare.
But a great step nonetheless! Hope they grow too.
I (we) have several customers with PVE deployments and VPNs etc to manage them. PDM allows me to use a single pane of glass to manage the lot, with no loss of security. My PDM does need to be properly secured and I need to ensure that each customer is properly separated from each other (minimal IPSEC P2s and also firewall ingress and egress rules at all ends for good measure).
I should also point out that a vCentre is a Linux box with two Tomcat deployments and 15 virty discs. One TC is the management and monitoring system for the actual vCentre effort. Each one is a monster. Then you slap on all the other bits and pieces - their SDN efforts have probably improved since I laughed at them 10+ years ago. VMware encourage you to run a separate management cluster which is a bit crap for any org sub say 5000 users.
PDM is just a controller of controllers and that's all you need. Small, fast and a bit lovely.
Proxmox Datacenter Manager = VMware vcenter
Proxmox VE = VMware ESXi
VE can be a cluster of nodes that you can still manage via the same UI. ESXi cant do that, ESXi UI is a single node, and not even everything that a single node can do with vCenter added.
Proxmox VE is both ESXi and some/most of vCenter.