The raised keyboard would not be very ergonomic, if you ask me.
Maybe the best fit for hardware would be an mITX or narrow mATX board with a Ryzen 2400G (nice integrated graphics) cooled by a AIO water-cooler with a 240mm radiator in the front under the keyboard. Then you should be able to free up space for a larger power supply and drives in-place of expansion slots.
Buy some SA Retro keycaps and use the keyboard as a showpiece. I don't expect anyone to actually use this board. It's kinda a waste to put a poker inside of it as those aren't that cheap.
But the concept itself is pretty neat, I wouldn't mind such a case. The only downside is the power supply and the price, 279$ at the moment and probably a retail price of 350$, you need some dedication to put that on your desk.