See here:
https://www.mobileread.com/forums/sho...65#post3400265
USB/OTG support has two major issues, one it needs a kernel change, two it probably needs a power source as well. The Kindle does this out of the box for its sound card adapter, Kobo does not seem to have anything like it.
It can be done in other ways, using charger cable, something I demonstrated in the first post of the thread above, or using wifi at the cost of wifi being a power hog; hardware modifications would probably work too, there is a serial port.
I'm not too keen on creating mods that mess with the kernel... one mistake and the device will be bricked (recovery system uses the same kernel as the main one), and there are strange issues/warnings when trying to compile the kernel version provided by Kobo in their kobolabs github repository, but that may be me doing something wrong.
But wait, there's still hope! You can buy this remote control at Amazon, it does not require software modifications:
https://www.amazon.com/dp/B0006PKZ1I/