I believe I understand that we can track visitors across domains using CNAME or Visitor.appendVisitorIDsTo - via a first party cookie
But what I don't get is, is this tracking relegated to my domains? E.g., mysite.com and blog.mysite.com and uk.mysite.com
Or can I also use Visitor.appendVisitorIDsTo to track across nike.com, bestbuy.com, target.com, etc.
And in either case, is this profile info permanent? Or does it expire after 1-7 days (per cross device analytics) or after 6-months if using the private device graph, or some other period of time?
The use case is multi-channel attribution and predictive analytics for spend by channel going forward.
Also, can all of this be done in Adobe Analytics? (The client cannot use the Adobe CDP unfortunately. They need everything hosted in AWS cloud or on prem)
Lastly, does Google Analytics offer this same efficacy in profile building, multi channel attribution, and cross domain tracking? I ask because I am trying to get them off of GA on AA!
Cross domain visitor tracking can be done cross domains and not restricted to sub-domains. This can be achieved using Adobe Analytics, given yo have implemented appendVisitorIDsTo correctly.
I have no expertise in GA , so I cannot comment on that.
Regarding your GA question, you might want to search for "GA cross domain tracking". I don't think this forum would be an appropriate place to discuss non-Adobe matters.