A pedal which would be ideal for a single guitarist who plays only with a rhythm section.

Basically Polyphonic Octave Generator and Synthesizer separately in one pedal. The Generator has all the cool functions and definitely foot controllable freeze. So for example when you play one note or a chord, you can freeze it, the generator section makes it into a cool big atmospheric background sound while you can play lead lines over it with the Synth. The sounds would be totally separate. It would be possible with both, mono and stereo outputs (in case of stereo, one output would be only generator sound and the other one only synth sound).
Then you add a harmonizer to the generator section. A 5th and 3rd and like Boss harmonizer or Ravish you can select the Major/Minor and the key.

Harmonizer and freeze foot switch would allow you to play for example like this… you play an A note, the generator creates an A chord while you play arpeggios or something else over it, then you hit a C note and let the Generator know it with the foot switch and play synth lines in C.