Is it possible to configure a vlan-backed connection to an Edge such that it would have 3 interfaces (1 WAN, 1 vlan-backed for OSPF to a physical network, and 1 LAN)? Currently the WAN and LAN are covered and working as expected, but I'd like to setup OSPF to a physical device for a single edge so was wondering if that's possible and supported? I see I can add an uplink to the edge and then enable OSPF on that interface, just want to confirm that it would be isolated to the 1 edge.
I don't see any reason why this couldn't be done. You can certainly have one or more VLAN backed interfaces connected to an ESG (up to 10). You'd simply create a new dvPortgroup with the desired VLAN ID and add a third interface connected to it. You'd then give it an IP and configure that new interface for use with OSPF. Just keep in mind you'll need a default or static route to send traffic to the WAN if OSPF has default originate enabled. Some more info on your desired traffic flows may be helpful to give the best answer.
Hope this helps,