Raising awareness on such topic and providing visibility to devs is a good thing. Unfortunately, numbers may be off by multiple orders of magnitude. It's really hard to get any meaningful CO2 number for a single API call. I'd suspect API burn much more CO2/byte than streaming.

Streaming is dumb, cacheable near end-users and heavy in bandwidth. API uses little bandwidth but often requires calls to multiple remote backend systems heavy in CPU, including subrequests to databases and other stuff. When you mix all usage and get an average KPI, it's no longer representative.