There are no Xamarin Android & Xamarin IOS SDK for the latest custom speech used by Microsoft.

We hope we can use the SDK ASAP, since we think Xamarin is one of the Microsoft core product and widely used.

I saw that currently only wav audio format is supported.
https://docs.microsoft.com/en-us/azure/cognitive-services/speech/getstarted/getstartedrest?tabs=Powershell

However, my customer is using Cordova App and the default format in Android Cordova is AMR audio.
We hope Azure Speech to Text can accept AMR as well.

This cloud services accept various format of audio including AMR, so I think technically it is feasible for Azure.
http://www.folio3.com/speech-to-text-services/

I haven't been able to find samples of the TTS anywhere.

Please provide a connector which can be used in PowerApps.

I have tried to use the service from the demo in an azure function, but this fails currently by an unknown error :(

The recognition of words like "tenthousend" is "10 1.000" but should be "10000" this is bad if you try to allow an Input of numbers bigger then 1000

This service is not doing a good job of capitalizing the first word in sentences. I say "I ate lunch period it was good" and I get

I ate lunch period it was good. This later becomes

I ate lunch. it was good

For some reason the recognition of a period in punctuation doesn't produce the capitalization of the next sentence.