[tgsovlerkhgsel]

In the US, there are commercial companies selling this data. Probably not associated with a name, but you could buy the data (I think they sell the whole dataset for a relatively affordable price), figure out who is a M&A lawyer by checking which IDs show up at their headquarters + some other relevant location, then track them from there going forward.

The data is likely collected from ad and analytics SDKs in various unrelated apps, so you just need the lawyer to be using one of these apps.

Journalists have demonstrated that the data is good enough to identify and track e.g. intelligence service employees.