Yeah outside mobile devices I imagine there’s a lot more leeway technically speaking. I’d be far more inclined to suspect a smart TV or a home assistant appliance like Amazon Echo, for example. And certainly there are plenty of PCs out there that are 100% compromised.
But it’s the phone that people often think of as eavesdropping on their conversations. The idea is stickier perhaps because it’s a more personal violation. And I wouldn’t put it past data brokers by any means. They would if they could. I’ve just yet to hear a feasible explanation of how they can without being caught. Hence my doubt.