Switch Platform is unacceptably slow -- anything that can help?

So, I have an app with many transparent PNG sequences which needs to run on android as well as some other platforms.

Unfortunately, it seems that it takes up to a few minutes for a single image to be converted. I have thousands of images -- I'm worried that my computer will never be able to switch platforms!

I looked into unity collab, unity cloud builds, and unity asset server -- none of these help to offload the conversion process. The asset server will hopefully make switching platforms back and forth manageable, but won't help at all with conversion.

Is there anything at all that can do distributed builds or speed up my process? Is my only solution to create a separate project for android and pre-convert all of the images via some other service?

Please help, this is a serious hurdle at the moment.