I do something similar to this with the GR-20…play a Gm chord, then step on the “Hold” button, and I can jam the intro to “Shine on You Crazy Diamond” for hours. The only trick is in order to change chords, you need to sneak the next chord into your playing, and step on the hold button again.
My fingers are raw just from playing on that patch.
There’s two synth blocks in the patch, they generate their own signal at the frequencies you program. Ext1 controller is attached to the shift control in the blocks, where you can specify the min and max shift so you get two chords.
Then with another parallel layout and amp, can and spacious reverb to noodle for hours.
There’s other patches that do that in the Axe-Fx too, that’s pretty cool too, as you can play a chord and run it through a bunch of blocks that make it sound like a synth pad, then rock the expression pedal, the sound is held and a you transition into a lead sound to noodle, pretty nice too.