Steam Deck and Dock Are On Sale for Steam's 20th Anniversary

You can buy the Corsair 1TB 2230 for $90 or the Micron 2TB 2230 for $137.

The eMMC is in the m.2 slot. You can just replace it with an NVMe.

The dock is useful if you either don't have a desktop/laptop system or if the Deck is more powerful than the system you do have.

Or you can use it like a switch and have the option to play on a TV with controller.