Unfortunately, you cannot get the id(gitlab internal id, iid) of an issue via the GraphQL Api, only via REST.
Is there any chance that this will change in the near future?
The Issue docs show an iid (Internal ID of the issue) field, so it looks it’s already available?
Unfortunately not, the iid ist just the the project internal id of an issue(example: #254)
An example for a gitlab internal id is gid://gitlab/Issue/27039960.
Ah, I got confused as you mentioned iid, which is the id within the project.
The global id is indeed not yet available.
I suggest you create a feature request asking to add this information in the future.
I came across this same problem today. I believe this is a bug not a feature request. Should I open an issue?
Based on the vision Gitlab wants graphql to be the primary API, yet it is impossible to use the graphql API to mutate any issues without also making a REST request first to obtain the gid. Even the getting started docs are unusable. At a minimum maybe that documentation should be updated.