I handle a similar situation by using virtual momentary buttons to trigger Alexa routines. For example, I change the inputs on my home theater receiver by creating a virtual button for each input type, putting that button in a Manually triggered ST Routine (formerly Scenes), and that virtual device triggers the Alexa routine that issues the commands to the receiver. And since the ST manual Routine shows up as a Scene in Alexa, I can use voice commands to trigger the scene. For example, here is the setup to change to my FireTV input: