As far as I can tell this would work, but having not bought a switch yet I don't know for sure.
Step 1: Obtain the official Switch Dock. Either the original or a second one you bought for $100 or whatever.
Step 2: disassemble the dock, and pull out the circuit board and carefully pull out the USB Type C docking port and it's cable
Step 3: Put the board and the Type-C port into a new ultracompact housing, like a 3d-printed version of the concept below.
Step 1: Obtain the official Switch Dock. Either the original or a second one you bought for $100 or whatever.
Step 2: disassemble the dock, and pull out the circuit board and carefully pull out the USB Type C docking port and it's cable
Step 3: Put the board and the Type-C port into a new ultracompact housing, like a 3d-printed version of the concept below.