This is actually what my network looks like but I'm curious if we know of any ISP doing this. They would basically have to sniff on the bridge between Wi-Fi and

This is actually what my network looks like but I'm curious if we know of any ISP doing this. They would basically have to sniff on the bridge between Wi-Fi and wired, or even on the switch if both ends are wired. I'm usually rather pessimistic but that seems rather involved instead of "just" spying on all the non tech-savvy users using the default DNS settings which should make up 99% of your user base.