Hello Xavier! The information is pulled from the Thread network. All Thread Border Router are named 'Apple Thread Router' with (XX) as the accessory naming. Similar would happen, if you use the free app Discovery on on iOS (https://apps.apple.com/de/app/discovery-dns-sd-browser/id305441017) or the version for the Mac (https://apps.apple.com/de/app/discovery-dns-sd-browser/id1381004916?mt=12). In the app at _hap._udp. you will find the Thread devices, at _meshcop._udp. your Thread Border Router (HomePod mini and/or Apple TV 4K 2021).
Best regards, Volker
Jan 7, 2022