Think about this: I just made a 3D game on the STES with a mouse and no game pad. Seems legit. So my idea is that platforms require certain research items, like TES needs game pad, and limits like Master V can not have 3D graphics. There could be a new research: controllers. There could be a controller for each generation, or each console. Also there could be genre and topic related things, and bonuses. For example, racers will get extra bonus for steering wheel support.
The option to research controllers like the Gamepad, the Mouse, and the Steering Wheel was removed in 1.4 because players found it too confusing (specifically, no-one could agree on what they did to a game). I doubt that Greenheart are likely to put that back.
When using a graphics tier with a higher tech level than the console, an average of the console’s tech level and the graphics tech level is used. I interpret this as meaning the graphics tier assigned to your engine is the maximum graphical technology your engine can support, not the only graphics it can use.
i.e. you use 3D graphics V2 on a console that only supports 2D Graphics V2; you aren’t forcing 3D graphics onto a 2D console, you’re just making high quality 2D graphics with a primarily 3D engine.