About three years ago this questions was asked. No I have same question. I have a DX project for managed package (namespace). The namespace is hosted in my private dev org. I wish to onboard a new collaborator to this project and I would like to give the collaborator an account with a platform license so s/he can create namespaced scratch orgs. Is this possible? I've only been able to get the cli to really work with the System Administrator/Salesforce License.
Yes, I'm aware of partner orgs. We will need to refactor to a new namespace and go this route when we ge serious about release but we're not at that stage yet.