- Wireguard Subnet: 10.20.30.0/24 - OPNSense: 10.20.30.1 - Raspberry-PI: 10.20.30.5 - Mobile Phone: 10.20.30.6
10.20.30.6 -> 10.20.30.1 -> 10.20.30.5 -> Internet (0.0.0.0/0)
If you use the plugin to do the routing you should only need to set 0.0.0.0/0 as the "allowed ip" on the data center side of the config and the home config should have the datacenter subnet as "allowed ip".
One other way to do it in opnsense is to assign the wgX to a interface and it's own gateway, that way you could controll it a bit better.