It sounds like you know this kind of business? What should the takeaway be for the rest of us that are not in the know?
The question I always ask, when evaluating companies making these types of claims, is "what hard computer science problems did you solve to make this possible". If you've actually done what is claimed like in the above, it will be an interesting list. In practice, this question usually elicits confusion.
There are legions of dubious companies making claims like this, which you can safely ignore. Their data quality is so poor that they would have difficulty violating most peoples' privacy even if they wanted to. The couple orgs with the technical expertise to actually pull it off competently don't talk about it.
(Built and sold a Data Broker, it's not a low margin biz btw, we had >85% gross margins because of how cheap the source raw data is, and we were doing double-digit millions $$ in revenue).
I've been paid to characterize the quality of this type of data from well-known brokers by discerning customers, and in my experience it is all varying degrees of rubbish from which almost no generalizable insights are possible. Even with data that is much higher quality than what you can get from app SDKs and adtech, ground-truthing experiments show that it requires very sophisticated analytics to build something resembling a generalizable model from which insights can be reliably extracted.
I know there is a lot of money in selling data like this but it is essentially a scam, promising insights that aren't really derivable given the data provided. The data quality has also become much worse over time, for a variety of reasons, which is arguably a bigger limitation these days than lack of a suitable platform.