but then you don't have the pull request feature, do you?

You push a branch and send an email.

Someone even made a simple walkthrough: https://git-send-email.io/

Software was developed before the pull request. Typically proposed diffs were emailed around. Presumably this is what the pull request is trying to emulate.

The anti-UI people want to use e-mail and command line tools.

It’s not a direct equivalent to pull requests because it lacks all of the easy history, inline commenting, comment status tracking, and ease of use, among other things.

I like little TIL posts like this, introducing new tools and sharing first-hand experiences with them. Working around restrictions (like using animations in Github Markdown) leads to this kind of creative stuff. I looked at the resulting SVG https://koaning.io/posts/svg-gifs/parrot.svg and realised that a lot of inline SVG elements are used within inline SVG within..the SVG. I've never seen that before. So thank you very much for sharing.

So one could make a quine: an animated SVG that shows its own source code being typed into a text editor

In Chrome you can just type "thisisunsafe" on your keyboard to open the page anyways.