[jsomau]

That is actually where I was going to start. Tracking the CO2 output for the production of millions of individual items across the internet is hard but I believe there are some services that can estimate CO2 for deliveries based on country + zip.

[Sholmesy]

even if you just did it from "city center -> the address on the postal" -> estimate gas -> CO2 estimation would be useful.

Lots of these suggestions are great, but honestly just focus on the first version.

Great idea tbh