Earlier quoted context omitted.
And yet if you want applications to work on your phone, many times you'll need approval from either Apple or Google. Google can effectively ban manufacturers (like they did with Huawei) from using "Android" by blacklisting them from Play Services. Apple owns the entire ecosystem and prevents third-party from having access to the same feature set.
Something tells me that the thing about Google not allowing custom Andriod operating systems to install apps is not quite true. I don't know about this specific topic yet, but I bet that if I look into it, I'll find out that there's nuance here that isn't been correctly portrayed by your comment.
If you want to use your phone like normal people do in 2025, and not relegate yourself to being a second-class citizen when it comes to simple things like paying for stuff, riding the subway, etc, your phone is either an iPhone or something that plays nicely with Play Services.
And that's just the remote attestation side. Many apps rely on Play Services themselves, and without access to them, will not work. Google gates access to Play Services through contracts, it is not open source or part of Android.