the idea is that the project ID wouldn't change, whereas the project path can change when a project is moved from namespace to a group/subgroup or any part is renamed.
The ID however is persistent (afaik).
I have found a few ways to get the project path via API, but I wonder if there's a way I could give a URL that uses the ID instead of the path, to send potential users to the repository front page, when referencing the project in a publication for example.
I can imagine a little webtool (http://www.gitlabidtourl.com/instance-url/id) that forwards/converts to a URL after getting the path via API. This would probably only work for public repositories though and using an external "translation" service seems impractical as well.