This could probably work, but remember that there’s a lot of tracking that happens by programmatic ad exchanges. To get a sense of this, look at the dozens of sites in a media company’s ads.txt, e.g. https://cnn.com/ads.txt

A big player like Facebook could ask media companies to set up fb.cnn.com or similar, but I imagine this is where we start to enter “security vulnerability” territory, where Apple uses different heuristics to ban this approach.