I don't live in the ad tech world, so I only vague know what is interconnected. Do the tech giants just sell info back and forth to each other?
For example, When I watch youtube on my Roku, if im not signed in, does roku still aggregate what I watched on youtube, could that be sold to Hulu, for ads when I watch that on the same tv?
I work in the CTV ad-tech space. Viewership data is highly guarded by every company. It's how every company is trying to differentiate themselves from each other. So, no, YouTube and Hulu etc wouldn't share information.
Ad data is known by the DSP that serves the ad (if the company doesn't serve their own ads), but viewership data is secret as a competitive advantage.
For example, When I watch youtube on my Roku, if im not signed in, does roku still aggregate what I watched on youtube, could that be sold to Hulu, for ads when I watch that on the same tv?