PC Keyboards are cheap, and often they cost quite nothing because some old kayboards lay around covered with dust.
I think of using more than one PC keyboard with VCV Rack. From my perspective there are 2 ways to do this:
platform-dependent with special drivers, especially for windows LuaMacros https://github.com/me2d13/luamacros comes in my mind
platform-independent: by using an Arduino to convert the inputs from a PC keybord into MIDI events
What do you think?