To which ad network are you referring? They have a couple: https://searchads.apple.com https://searchads.apple.com, https://support.apple.com/en-gb/guide/adgui

To which ad network are you referring? They have a couple: https://searchads.apple.com https://searchads.apple.com, https://support.apple.com/en-gb/guide/adguide/apda0878bbd9/icloud https://support.apple.com/en-gb/guide/adguide/apda0878bbd9/i.... They cover ads in Apple News, the App Store Search ads and promotions, and there's the results of Siri search I suppose too. But all of these are internal Apple products and marketplaces. They are not running advertising auctions to any bidder on the basis of guaranteed user groups or targeting strategies. If you are in fact suggesting that they sell ads beyond their internal marketplaces I'd consider that motivation to move away from them myself, and I converted away from OSS when I got bored fixing my workstation more than my work.