Is there a solution for supporting "find my phone" from either Amazon Alexa or Google Assistant, using the native Android Device Manager? Or does Google even provide a web services API that could be used to develop this?
My Google Home does not (yet) support this, which is a bit surprising, given the integrated Google ecosystem: "Sorry, locate device is not yet supported."
Alexa depends upon a 3rd-party integration, with TrackR and IFTTT seeming to be the most popular ones. TrackR requires an additional app - and initial experience shows it to be a battery hog. The only IFTTT applets I've found rely on calling the phone, which won't help much if it is on silent.
Using the native Android Device Manager support would seem to be the most ideal here - as it wouldn't require any additional software, and can ring the device even if it's set to silent or vibrate.