With a bit of luck and a lot of trying, I've been able to figure out how to add Markdown support to wordpress via the REST API. This servers as a reminder to myself, and I hope it helps someone else if they come across this.

• REST API is enabled by default for wp v4 and above, so all good there
• Default Auth only has cookie support, and since I'm looking to interact and make quick publishing as easy as possible, this will not do.
  • JWT Can be enabled with this plugin , so that solved that.
• Now we can post without the admin dashboard, how do we get it to format the markdown? We can add another plugin that gives us wp-com support for markdown in Posts, Jetpack.
• With those enabled we can stringify a markdown file, and HTTP POST it to our wordpress endpoint and BOOM 🎇 we've been able to write in markdown, and send posts.
• Next item, post and publish in a single request? Possibly ?