This is probably a commercial Android distro like Samsung's or Google's, filled with OEM crapware. Pure Android is far better than that and is free (freedom to install apps, inspect the source code, etc.) It's basically a Linux distro for smart phones.
It doesn’t really matter to me if there’s some other specific version of Android that fixes some issues if I install it. As a user that’s not something I care about.
It's odd because, as someone who daily drives a Pixel with GrapheneOS and also owns an iPhone, my experience is the opposite. You could not pay be to go back to a device controlled by a corporation, and on which I am not allowed to run programs without Apple's blessing. The UI is largely a matter of taste, by now all mobile operating systems have converged to a broadly identical design and similar gestures etc.
Both are inconsistent mess.
Not having the ugly frosted glass thing is a very big plus.