Chop to feedback ? pointcloud disintegration issue

Hello td community :^)

I am currently working on a documentary film, and making a lot of the animations in TD. I think this is a simple question (hoping) but I have been struggling to figure it out, really hope someone can help or point me in the direction of a tutorial.

I have made a pointcloud from an image, using a grid and chops. Like this tutorial : https://www.youtube.com/watch?v=3xNk2FgFKiM

It works and looks just as I want it. However I need the pointcloud to start dissolving after a while, using the animation comp.

I would like the dissolve to look like this :

but this is from a 3D model, and in my setup the pointcloud is a chop before it becomes a geo. And I can’t connect the chop to a feedback to start the disintegration of the image. I really hope someone can help me…?

crossed fingers and thanks a lot in advance