I write everything in Markdown with ia Writer Pro on macOS and iOS. Its only drawback is no share sheet. Can you use existing automation tools to provide share-sheet functionality? I will be happy to pay you in dollars, or DW points, or jewelry, or donation to your charity of choice.
On my iPad, I've got Draft, Workflows, and ia Writer. I want to select text in a variety of iOS apps and send it to ia Writer Pro as if there were an ia Writer share sheet. (Apps I use often include Safari, Chrome, iBooks, Kobo, KyBook 2, Libby, Instapaper)
I already have an "open in IA Writer" action for Drafts.
The tricky part is: can Workflows reach inside Drafts to trigger the "open in IA Writer" action?