This is cool! Still reading over the wiki yet, but do you know what they term multiplexing controllers as? I'd like to learn how they implement the same controller assist functionality for merging simultaneous inputs for the same axis.
There's very little documentation on how the property game consoles implement this accessibility feature, and I'd love to learn how others have implemented the signal mixing logic from a multi user input perspective.
Encountered an odd Bluetooth issue last week with a motherboard that had a combined Bluetooth and Wi-Fi radio chip set. Wi-Fi worked, but the Bluetooth hardware wasn't even detected. This was after migrating from a Windows install with known working Bluetooth drivers on the same motherboard.
Found a solved thread for the same motherboard SKU where power cycling after disconnecting the desktop power supply from AC for 30 sec resolved it. Didn't believe it, but tried it anyway and it worked. Guessing the Windows driver must have put the Bluetooth transceiver in a funny state that the mainline Linux kernel couldn't recover, but resting the chipset with a through power cycle with internal voltage supplies zeroed made the difference in re-initializing the hardware.
Just a wild suggestion...