Google Ads (used to?) lets you target by "bahaviour" vs "in-market". They can tell the difference between someone who is passionate about beds, maybe involved in the bed business (behavior) and the people who are making the once-in-a-decade purchase of a bed (in-market).
Google can tell devices apart on the same google account and keep together search threads. I might be programming on my desktop making engineering searches but at the same time I'm googling memes on my phone; both logged into the same account.