Currently, there is no way to allow developers access to test data only. I don't want to give them access to production data unless I absolutely have to. It's full of sensitive data. So the only "solution" is to set up the whole Mailchimp service 2x, to have everything duplicated.

Please come fix this. Just extend user permissions so that one can select a checkboxlist of domains they can access across the entire dashboard, api.

Take Cloudflare as an example for inspiration.