Hmmm is there a way I can get it to work by installing packages myself? Perhaps RDMA drivers from Mellanox or Intel? Surely there must be a way to get it working on Proxmox...
There is currently no support at all.
But it is a Debian, you can always manual install and configure.
However, you won't get any support even with subscription.
This is not really on the roadmap. Maybe you can create a feature-request....