At 2TB SSD, you should compare to the $1350 steam machine instead.
The GPU isn't exactly equivalent. Gamers Nexus puts it closer to RX6600 performance. But that ignores the RDNA3 improvements so I don't really have a good comparison for that.
They did announce SteamOS for general computers, so I don't expect game support to be too different.
Would it be difficult to make a PC with a similar power/performance profile?
It wouldn't be surprising if Valve's efforts at integrating the unit (putting the relevant chips on a single board, eliminating anything unnecessary, and improving cooling) could shave a significant amount of power.
The Steam Machine is about a 6" cube. That's ~3.5L in volume. This case is ~33.6L. 33.6 / 3.5 != 4.
PCPartPicker Part List: https://pcpartpicker.com/list/3WkCdq
Price: $1021
So if you want something small, it's a bit more expensive