One of the possible problems with the Alexa idea, or any of the doorbell etc. ideas, is what if you are using P/T or Tablesaw etc. with ear defenders when it goes off, you won't hear it, and when you stop will have no idea it went off. I have been looking at something similar so my wife can alert me when I am in the workshop. I have been thinking of an Alexa enabed power socket which activates a coloured (red?, no smutty comments please) light in the workshop. That way I will likely immediately notice it, but if I have my back to it will see it as soon as I turn around. Obviously it really depends on having the right kit such as wifi in the workshop and house of course.