UniFi + PiHole + Unbound -- Block specific sites by MAC address & Subnet

My general set up are several Ubiquiti Switches, APs, a UDMP, etc. I have multiple VLANs which ultimately intertwine with a PiHole and Unbound running on the same VM on a Dell PowerEdge R420. I have three small children all homeschooling due to the pandemic and need desperately to block YouTube from a series of devices, in two specific cases: 1. Specific devices (by MAC address) on one VLAN. 2. All devices on a second VLAN. I know the PiHole can block devices to a site/regex by MAC, but only by one hop. So given the number of switches in my network, this doesn't work. I'm hoping this is something that can be done with either Unbound or another *nix utility that I'm not aware of. Suggestions?