Speech Recognition engine question on Windows

Question

Hi MSFT member,

On windows, when developing a Speech recognition app, there are about three solution APIs:

1. Windows.Media.SpeechRecognition
2. System.Speech Programming Guide for .NET Framework
3. Microsoft Speech API (SAPI)

Since We want to use local offline solution, Azure speech service is not included.

Q1. if OEM want to customize a new SR engine, which solution do you recommend?

Q2. for Windows.Media.SpeechRecognition we did not find how to set SR engine, does it support customized engine?

Q3. If OEM can customize SR engine, how to make a custom SR engine? Do you a guide document to make a SR engine? Is there any restriction?

Thanks.