You need "allow in, destination OPT1, OPT2" on your LAN interface.In 99% of all cases you only use "in" rules on the interface where the connection is initiated.
They all have the OPNSense as the default gateway. I test this from WG0 and OPT2. I can ping 192.168.60.1 from OPT2.Could it be a routing problem?
Back to LAN to OPT2. Should work. How is OPT2 setup, do you have a switch plugged into it, or otherwise describe the physical setup please.