It's not necessarily true you have to look. BTT lets you define actions for sliding 2/3/4 fingers left or right on the entirety of the touchbar. You can set it up to change volume, brightness, ctrl+tab, change the size of a drawing tool, undo/redo, whatever. It works anywhere on the strip, so it's very forgiving.

I actually only just now thought of mapping 3-finger swipe to undo/redo. I've only been messing around with it for five minutes but it's kind of nice, honestly! It's better than cmd+z when you need to undo/redo more than once, because it bypasses the key repeat setting.