The Deck’s power management features are a solid selling point. There’s no reason they couldn’t be implemented elsewhere, and it would be a boon for other portable devices for sure.
I haven’t used the Ally, but the Deck’s touchpads are just intuitive and functional, it seems so obvious in hindsight that it’s actually shocking that nobody had thought to put them on a portable until now. They work great for replacing a mouse in mouse-focused games, and for navigating desktop mode. Much more effective than navigating with a joystick.