@randyth pointed out in another thread that There is now a brand new Alexa skill which should enable you to achieve the outcome you described in your first post, but you have to have some technical skills and you will have to use something as a “man in the middle” ( which can be the IFTTT maker channel, which gives you smartthings integration).
So it would work like this.
One) smartthings recognizes a first alert event and turns on a virtual switch
Two) that virtual switch coming on is the “if” in an IFTTT applet
Three) The “that” in the applet is the IFTTT maker channel which triggers an Alexa skill called “notify me”
Four) The skill causes echo to do the Bing sound to tell you that you have a notification
Five) you have to ask echo what your notifications are
Six) Echo will then say all your notifications including speaking a predefined notification that you have set up.
This works because in March 2018 Amazon opened up the notification capability for some individual skills.
So you are going to be limited to events that smartthings can recognize rather then connecting the first alert directly, but it can now be done.
However, don’t bet your family’s life on this working reliably
There are so many places this chain could break, particularly in the event of fire. The first alert has to communicate with SmartThings, The Internet and SmartThings cloud have to be working in order to communicate with IFTTT, the Internet has to still be working in order for IFTTT to communicate with echo, any Internet has to still be working again in order for the message to get through to your echo. Then you have to be aware enough to ask echo to tell you that you notifications. All while a fire is burning in your house.
So as an extra thing, maybe, but not as something you actually rely on.
I think this notification is much more suited to stuff like “Amy is home” or “the mail has arrived” or maybe a leak sensor. But not stuff that could endanger your life if it doesn’t work well.