Adrian, you should be able to view metadata through the API, even if its not published, as long as you have set up an API token to authenticate with.
I’ve attached a link to the API training that covers what is need to do to set this up. https://aristotlemetadata.sharepoint.com/:p:/s/Training/EYEFzKVDFyhOtmhGx7ioqK0BGiR6OFkEdlVFRmPQQb_wjg?e=jlzdvp
The two necessary slides are also below:
Hope that helps!
Also, we’re planning on setting up a developer specific help site that covers the API and if you’ve got some suggestions on how we could handle this it’d be appreciated.