Awesome. Please update us here when you do. I’m very curious to find out what libraries you’re building this on top of. I always thought Prosemirror would be a good foundation for WYSIWYG in Discourse, since it is also using @vitaly’s excellent markdown-it library.
Also, are you doing this as a personal project (i.e. for the fun and challenge of it, and scratching an itch) or is this work being sponsored in some way? I ask because within the Meta community there’s huge interest in rich editing, so there are a couple different avenues we could explore to support this work.