I'm so sorry for the delay.
Unfortunately I don't have good news for you at this point. I need to think it through a bit and see whether I can come up with some workaround.
Here are the big issues that you will face right off the bat:
Finally, would you mind share your .rptx file - the report file that you generated in ArcGIS Pro here. I can use that as a starting point.
Okay, I got something for you try. There are few hoops that we need to jump thru. That is because all the limitations that I mentioned above.
I will try my best to explain:
Here are two things that I have attached here:
What changes I made in .pagx & .rptx files:
What do you need to do:
Please let me if you run into any issues.