Hello there! A USB footswitch should work perfectly with your Max patches. Just note that a USB footswitch is essentially a single-key keyboard – there is no MIDI is involved. As such, you will be using the “key” object, configured to listen to whichever key your footswitch spits out.
If DIY is an option for you, it’s also worth mentioning that you can build a true MIDI footswitch to your own specifications and without much difficulty by using a Teensy USB Development Board. The board is tiny, so you could throw a few footswitches in a single 125B or 1590B pedal enclosure. That would be a lot more durable than the plastic USB footswitches. You can even wire up a jack for an expression pedal.
Hope that this helps!