I think you are ignoring the use of location-based tracking and other correlation techniques. A bunch of different 5G appliances can all figure out their positions quite accurately from 5G signals and decide they belong to the same household.

And, that's before you consider that they can also scan local wifi and bluetooth spectra to glean even more information about their local environments. With participation of vendor applications on phones, they could also use ultrasonics or crazier things like modulated LED lighting.

Finally, if one of those devices is compromised, it can then be used to launch local attacks via wifi and bluetooth, or even potentially those other covert channels if they can exploit sloppy code in those other dark apps...