Users can specify a username and a snippet URL. The GitLab instance's domain can be inferred from the URL.

The snippet API appears to be unauthenticated, e.g. https://gitlab.com/api/v4/snippets/2364183

Once we verify that the gist owner matches the username specified, we can do something similar to GitHub Gist (check file content).

9 days later

Ohhhh cool! The API's response is great, contains the author and the content, all we need.

Right, so now we want to have multiple ways for a single service provider, right? Given that there already is a way for GitLab.

This is not supported just yet but shouldn't be too complicated to fix.