I am able to get HA installed on UBUNTU via the SNAP. Running version 2025.10.4. I configured the USB port of my USB PLM to be used my Ubuntu Guest in ProxMox. Was able to install the Insteon Integration and it recognized my PLM on the USB port. I have about 40 Devices linked in my PLM - but the Integration only AUTO discovered 1 lamp module. I can control this lamp module from HA - and - HA shows correct status when lamp is actuated locally. For a test I MANUALLY bidirectionally relinked a second lamp module with the PLM. That module appeared in HA about 20 minutes AFTER the relink. I just relinked an appliance module with the PLM. Do not see it in HA yet. Is this expected behavior ? Am I missing something? BTW - I can see the ALL-LINKS DB in the PLM too.
Is there a reason you are not running HAOS on Proxmox?
I really like Ubuntu… and I like to make my life harder… 
Since I am having issues with my setup - I think I will just run HAOS straight under Proxmox. Then I can get my Insteon and Z-Wave stuff checked out with a standard kind of installation.