Setup guide Proxmox, Opnsense, HA, OpenWRT

So I bought a fanless firewall appliance with 4x2.5Gbps ports and I would like to setup Proxmox on two identical SSD drives. I also want to configure a bridge on my ISP router and then configure the router as a firewall on top of Proxmox. My plan is to install HA on top of Proxmox too....