you can assign the Bypass controls or any other parameter that can have a modifier to Control Switches. the catch though is nothing else can control that parameter at this point. so a Control Switch on the Bypass of Drive means a Scene cannot change that Bypass anymore.
Channels cannot have a modifier, as they are not a parameter, so a Control Switch can't change channels at this time.
Fractal designed the FC controllers (including switches in the 3 and 9) to directly control blocks on/off and other various things, and it's not transmitting over common MIDI, allowing a common XLR cable for connection. as of now there are no "general switches" like a MIDI controller.
an advanced MIDI switch that can have multiple commands on a single button press could be programmed to send Drive Bypass, and Amp Channel change, for example. i've used a MMGT from RJM and it allowed this. i believe Morningstar and similar recent controllers can do this.
maybe the FCs one day will have a "general switch" setup allowing whatever messaging we want, but the current FC communication is extremely complex already with so many if/then's handling all the sync.