Grant some user access only to issues/milestones, not codebase. Or how to clone project and remove codebase from new one?

I have a project and we're adding some new team mates, but we don't want to grant the access to the codebase, but would like them to be able to use the issue tracker (we use that for non-technical issues too). I can think of two options of doing that:

1. Have a way to grant access to users only to the issues, not to the code. This doesn't seem to be possible though currently.
2. Export the project and import it in a new one (also on gitlab.com) and then remove the codebase from the new project (and the issues from the original project). Thus the new project will only have the issues (history included - thought not a must) and the whole team can use that project for issues, while the original project will only have the code.

The issue I seem to get when exporting/importing is I get this error from this issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/35580

I didn't add this question to that issue as I feel like this question is about a different topic. I don't necessarily need to do export/import, what I need is separate user rights between code and issues. So maybe there's another way to do it without export/import and I didn't find it in the docs?!

Thanks.