Dunno about MAKING one, but If you're running AE 2018 or earlier (all the way back to 2004) you can call up Color Finesse and presto! you have a working scope. 2019 or later you can do something similar with Lumetri and Lumetri Scope. Maybe record them in action and time ramp?
I would think making one would require quite a bit of coding but I look forward to other answers.
By extracting each channel to a seperate comp, and then using PixSort; I was able to sort each pixel by their luminance values for the three different channels.
It looks like the mix of parade and a histogram - so not completely realistic.
The only problem is the speed. PixSort is extremely taxing on processing, so it takes a good few 15-20 minutes to export 10 seconds.