@brandon I think you're overcomplicating it by considering power plant differences yourself instead of working with a known average. The question is "what is the difference in co2 output between the ryzen and Rpi." The math can be simple, (x-y)*(z) where x is the kw/h of the ryzen, y the kw/h of the RPi, and z our average co2/kw*:

(0.07-0.006)*512 = 32.78g/kwh difference in output.

* there's debate about what "our" average is, I went for the U.S. https://blueskymodel.org/kilowatt-hour