GlassWire appears to work for at least some users running attached devices, e.g. those who have complained that GlassWire treats the usages all as one computer.
- Internet Connection Sharing (ICS)
- WiFi hotspots
- tethered devices.
Others have said ICS didn’t work but maybe they never restarted their computer!? Anyway, the GlassWire team may respond with a more definitive answer.
Here’s a couple of relevant topics where this has been discussed: