i use wheres my droid on android to find my phone… it will ring, raising volume to max even if off, and flash even if phone is locked in addition to sending you locaation… I mostly use it to find my phone where i left it somewhere in the house and cannot find it.
Anyway this works via specific text message or a call from a specific list of numbers… I upgraded my phone to android oreo and the ring feature no longer works and support cannot figure out why (probably some permission or not allowed anymore in oreo). Anyway, long story short the message activation still works.
So I created a virtual switch since these are all Alexa can control. Added a rule to send me a text when the switch gets activated and turn it off.
Added an Alexa routine to turn the switch on when I ask her to find my phone…
Hope this helps someone with similiar issues.