It lets you trigger Alexa routines using a HTTP API to press a “virtual button”. Can be used, eg, in Home Assistant to get announcements (“Garage Door is Open”, “Washing machine has finished”) or anything else Alexa can do in a routine!
Now it’s nowhere near as flexible as the alexa_media_player plugin; it’s a write-only interface… “press this virtual button, trigger a routine”. But it’s written totally with official APIs and shouldn’t(!) suffer the authentications issues as a result.
It’s also not very polished (no pretty UI). But it should run perfectly inside the “Free tier” in AWS.
The documentation includes a couple of examples of how to use it in an automation action.
Maybe other people will find it useful.