My first thught is the Heavy Industry Malekko Sneak Attack-this will absolutely give you what you want in this respect, and it sounds great with the H9.
My second thought would be programming a volume/expression pedal. You could easily set all the parameters for just volume, or anything else. I realize this is not exactly a foot-free solution.
Seems strange to me that it’s so difficult to find an autoramp/decay patch for your needs-it’s fairly basic. Please keep me updated on your solution!