As you and Bernie suggest, they will be doing lots of speculative security research to find vulnerabilities in consumer products, be it your TV, phone or car.
On the one hand, it's hard work. It's a moving target, both in terms of the narrow window between products being introduced and becoming obsolete, and in terms of bugs being fixed. It may be useless if your person of interest that you don't even know about yet drives the wrong car or uses the wrong kind of phone. And it depends on use case. They develop the means to hack your car but you haven't bothered to pair your phone, so again it's no use.
But on the other, overall it adds up to a broad capability set, and can yield surprising dividends. Hack into a Jeep, say, and you've probably got the same capability across all Fiat-Chrysler vehicles of that era, because the software is common. Breach a version of Android in some core way and you're talking big numbers.