Raspberry Pi 500+ boasts a high-quality mechanical keyboard with removable keycaps and individually addressable RGB LEDs, an internal M.2 socket pre-fitted with a 256GB Raspberry Pi SSD, and 16GB of RAM.
This is a cool piece of tech but I can't really think of real world use cases besides looking cool and having that weird but cool computer-in-keyboard retro vibe. I had the same idea with the 400.
Maybe the best use would be some sort of super portable thin client, but looks very capable to be just that. Having a battery would have made sense too, for portability. Any out of the box way of connecting it to a smartphone screen would be great too, even if it's just tty.
Maybe I'm just being obtuse and just want a laptop, but the whole thing seems impractical to me.