Knowing how Apple operates, they'll do anything to build the solution around their proprietary crap and while using open tech under the hood, never contribute anything back.
I am yet to discover a game that can't be played on the Deck. Steam Input, the touchpads and the gyro are great at getting a good control scheme for everything. I even played StarCraft on that thing.
Yup, I find analog stick plus touchpad to be perfectly adequate for most of my m+kb games. I'm not sure I could make it through a fast twitch shooter like Doom on it, but for the most part it works just fine.