Very interesting! Tangentially I've worked a lot with video streaming, and one technology that there was a lot of buzz around was to splice personalized ads into regular linear TV broadcasts. Basically it replaced the original broadcast ads with personalized ones, completely seamless and unnoticeable. I don't know if it was ever implemented, but it sounds like it would tap into the same mechanism that you propose.
It did, under the name server-side ad insertion (SSAI).
https://videoweek.com/2020/08/12/server-side-ad-insertion-ex...
I suppose the ultimate combination would be targeted advertising inserted into broadcast streams, to fool you into thinking it’s a shared experience. That already happens with the sideline billboards at big sporting events.