“Gurman says Apple won’t “shoot themselves in the foot” by adding it everywhere, and will probably introduce the feature quietly and without fanfare.”
Apple says iPhones need a single App Store for security. According to Mark Gurman, the security argument ends exactly at the EU border, where the Digital Markets Act forces sideloading. Developers who distribute outside the store will reportedly pay extra anyway. If sideloading were dangerous, Apple would not sell it to Europeans for a fee.