pfSense comes with a fairly closed default firewall. You’ve done a decent job of describing the physical configuration of the network. What is the logical configuration? What VLAN(s) have you set up? In the firewall page, what tabs/headings are there? At minimum, you should see “Floating”, “WAN”, and “LAN”.
Also, includes the networking config for Proxmox and the pfSense VM. You can grab those details from the Proxmox GUI.