There are a lot of companies in the cross-device graph space. As I said, they do not have nearly the level of integration described in the great-grand parent comment.
If I'm wrong, sign up with Liveramp and use my phone number to tell me what restaurants I've booked reservations at in the last month. Is that how it works?
So yeah the restaurant or restaurant group doesn't have that great of a profile, it is built by companies like liveramp who get data from tens of thousands of sources and pool it into their own graph + audience data. Then they license it back out to those same companies. FB/Google and Oracle (crosswise) probably have the best identity graphs and are on par with what the original comment was describing. (I used to work at oracle on their audience products)
Liveramp is b2b and definitely won't support anything you want to do with them, but there are some comically bad tools (haven't been updated and are purposefully inaccurate) that let you check what data pools you're currently in.
If I'm wrong, sign up with Liveramp and use my phone number to tell me what restaurants I've booked reservations at in the last month. Is that how it works?