Based on the lack of responses, it appears there’s no way of getting this to work unfortunately. So I found this post (How to enable "Play Message on Speaker" as an Action for a Routine - #2 by KenW48360), regarding playing a “message” on a speaker which got me wondering if I could get one of my Echo Dots to play the MP3 audio file triggered by the automation (which I could connect to my wireless speaker). Any ideas on this one?