I didn't know of the specific "request-pull" subcommand so thanks for that link. Still, both things you link are a bit different from how GitHub implements it, and I'd be very surprised if the HTTP API you link includes an endpoint for triggering the request-pull the way that GitHub has such APIs for their pull request mechanism.
If you meant to say that git can do anything GitHub can and we needn't use GitHub, I agree. I've used git in peer-to-peer fashion before, and especially now that it's Microsoft's, I think twice before opening repositories there. But if your main point was rather that git includes the same functionality as GitHub and that OP could have just tested the regular git instead of doing it on GitHub itself, I still think that's a rather different test target.