With the addition of SendLater in messages for mac and ios is it possible to do from drafts?
To the best of my knowledge, that feature is only accessible in the Messages app itself and not available to third-party app integration (including Shortcuts) in any way.
This is probably a bit old school compared to the new OS releases and the integration you are after, but one of my favourite uses of the app Due, over and above the constant nagging USP, is to schedule “send later,” messages. Due supports x-callback-url, so with a Drafts message action, it’s easy to send a message to a particular contact when the alert pings in Due.