It's not irrelevant to the FCC, a United States federal organization. I don't think any brokers are selling "execute code on 10s of millions of US citizens' phones" to foreign entities, and if they were I suspect the FCC would have something to say about it.
Data brokers are absolutely, 100%, verifiably selling data collected by large american tech companies and selling them to foreign actors. See: Emerdata for one example. Yeah, the FTC makes attempts to take on these companies, but only if they find out about their activities, and even then, only years after the fact.