One thing I miss about using the native wikitext editor is the specific-to-en-wiki toolbar at the top that has the redirect syntax. I always forget it and now I always have too look it up .
Creating a redirect is not a particularly common action, and I'm worried about cluttering the toolbar up with buttons for uncommon actions. There's probably some way of doing this that doesn't add clutter; that needs design time to think about.
It's a common action when creating a new article. It doesn't have to be present except for "create source".
Or it could just go into the "insert" menu - that wouldn't clutter things up mcuh.
I would avoid loading full editor at all for this task. I would recommend to hide the option in editors as low as possible (backwards compatibility and maintenance work) and create a new menu entry next to "move" page button leading to simple OOUI text - button interface