Well, that's actually the default for WireHub. Routing between peers (ie their generated AllowedIPs configs) by default only refers to the IPs of the two peers

Well, that's actually the default for WireHub. Routing between peers (ie their generated AllowedIPs configs) by default only refers to the IPs of the two peers and you can use an Interface per Device per Network, so that you'd need to explicitly enable the relevant WireGuard interface for each network. But, re-reading your comment, as long as your networks are on different CIDRs you could use a single WireHub interface to refer to more than one device/networks. As I said, traffic by default is routed to the specified peer's Address not the whole network (eg, 192.168.x.y/24) nor the internet (0.0.0.0/24).