We are trying to use sfdx only to spin up scratch orgs with desired configuration (we have a standalone config file, scratch-org-def.json to feed to force:org:create command).
Our project is in old metadata format, i.e. it is not a DX project at all.
After spinning up scratch org, we are deploying project metadata with the help of force:mdapi:deploy
So basically we've just replaced dev sandboxes with scratch orgs (since it's faster to spin up them), but still continue development as for old style sandbox flow.
Now we'd like to spin up scratch orgs with a namespace of our managed package. We've already linked namespace to our dev hub org. But as I see in order to specify namespace, we need to have truly DX project structure, i.e. with sfdx-project.json file (that's where namespace should be specified).
How could we just spin up scratch org with namespace but without setting up DX project structure? We would deploy our classic metadata to such scratch org with namespace to debug different packaging issues etc.
Any help would be appreciated. Thanks in advance.