I'm sorry, but how is it "nontrivial" to change phone platforms? Google says it's easy and all you need is a cable to get the best experience: https://www.android.com/switch-to-android/
Your iMessage history disappears; Google can't transfer that to your Android phone. They claim to be able to transfer SMS/MMS history, which surprises me: I'm not sure how they accomplish that. I'm sure there's a ton of other user data that they also can't transfer. (Speaking of iMessage, any group chats you were in are now broken.)
Google of course has an interest in telling people that switching is easy and painless. It's not, though.
Everything else you mention is part of the nature of changing operating systems: software incompatibility / unavailability. That never has and unfortunately never will be solved. It’s hard enough to keep old software working on new releases of the same OS.
You can't force everything to be uniform and support all of the same features to make switching between manufacturers of a product-class "trivial". How's that part of a healthy free market? Requirements to that effect kills all creativity and specialization of products for different purposes. Android and iOS are different and that's a good thing!
You shouldn't. It's a marketing page.
This argument doesn't work if you don't believe the part about getting all the same apps, which is objectively not true.
It's a fun way to mock google, but it has nothing to do with the merits of this issue with apple.