AD tech would seem to be more definitive than polling but much harder to package for the voter and decision maker. If your phone is telling me (presume I have access to ad tech data) that your device loves articles about how evil Trump is and you have many emails coming to the device from NeverTrump groups, i'd say that your device is owned by a likely Biden voter. I don't think we have bridged that gap between what advertisers are getting out of this and what politicians can't yet say that they are getting out of this technology.