[danw1979]

Leakage doesn’t seem to be the problem that is being explained here: it’s internal sensing within the home by existing wifi devices.

[Communitivity]

It doesn't need to be your wifi devices, it could be your neighbor's, if you're in a townhouse or your house is close enough.

But I agree with another commenter: if they've hacked your wifi router then you have bigger problems, as they've likely hacked all your devices then.