Samsung Washer and Dryer Announcements via Amazon Alexa

I wonder if it might take some time for those to come over? Or maybe if you remove those devices from the SmartThings app and re-add them Alexa will then detect them?

You can also try to create a virtual switch in SmartThings that Alexa can see, then turn on that virtual switch in a SmartThings routine when your washer is done, and do an Alexa announcement when it detects that the virtual switch has been turned on. It might be a little tricky to set that up if you’ve never done it before, but here’s a link that talks about it: