That's not really a good solution though. For most people, setting up devices with mDNS would be it's own kind of hell. Also, some other standards strongly rely on mDNS to even function (like Matter devices).
You need a router that allows you to configure strong policies, such as client isolation, what data can flow between VLANs, etc.
More broadly you cannot solve every with technology. The most effective route would be to simply outlaw such analytics without informed consent. This is basically what the GDPR does, but it takes a while before enough companies get fined before the industry understands. That said, the last few years, products sold in the EU are starting to get toggles to request analytics that are _off_ by default, etc.
But blocking that device at the home router cannot prevent the radio on the device to keep using the Wi-Fi bands or creating it's own access point and in both cases pollute the spectrum and slow down every other Wi-Fi device.
If the device does anything with network, other devices can likely sniff a lot of information about it with high degree of accuracy based on how they react to certain network probes.
and my point was that you can prevent this by using e.g. WiFi client isolation and isolating VLANs (while still using the 'smart' features of said device).
I am not sure how your comment is a reaction to what I said?
You need a router that allows you to configure strong policies, such as client isolation, what data can flow between VLANs, etc.
More broadly you cannot solve every with technology. The most effective route would be to simply outlaw such analytics without informed consent. This is basically what the GDPR does, but it takes a while before enough companies get fined before the industry understands. That said, the last few years, products sold in the EU are starting to get toggles to request analytics that are _off_ by default, etc.