I want to provide an automatic notification on Patreon when my scheduled content is published on my Wordpress blog. I’ve read that Patreon’s API doesn’t allow that sort of thing, but is there any workaround for automatic posts?
Yes, write operations are not supported at Patreon api yet. So making a notification visible at Patreon could not happen. Even if there was api support for it, then there still would be the problem of having it as a feature because it would require changes to Patreon.com
Best way could be to mail your patrons via your WP site or via Mailchimp (or other integration). That would require coding obviously, and that you keep the list of your members synced to your WP site as users.
Alternatively One Signal and other push services may also be used - that may be a good idea. But would require more coding since One Signal doesnt distinguish in between users i believe.