… Is there a way you can change the Mix of the Pitch A and B in the Shimmerverb relative to each other?…
I meant to try this out (but did not): Use Low Band Decay & High Band Decay as your ‘pitch mixer’, and Pitch Decay as the master level of total pitch shifting.
I think the success of this will depend on the intervallic distance between Pitch A & Pitch B. Opposing octaves may be easier to dial in. Upward shifts with P4ths & P5ths might be difficult. Any significant amount of Delay time could smear everything back together when it’s recycled.
https://cdn.eventideaudio.com/manuals/h90/1.1.2/content/algorithms/reverb.html#shimmer
Best I got for you.