RDMA over Thunderbolt is going to be used only with Mac devices. Apple has a history of keeping things within their own ecosystem. You gotta be insane to think that they are going to just magically allow you to plug in a graphics card and it will work natively.
The point of bringing up Android is because that is what being dev friendly. Samsung or Google have nothing to really gain to enable the desktop mode. But they do it anyway because it increases the usability of their devices. Ask yourself again, if Apple already runs arm on all of its devices, why not enable a desktop mode for the iPhone? Its EXACTLY for the reason to squeeze more money from consumer. Its why they do the thing they do with app store, that why they own all the advertising streams on their devices.
So if you wanna stay deluded about what Apple does, be my guest. Just don't be surprised when nothing turns out like you hoped.