How to ask Siri to Change TV input

iOS 12.2 Introduces the Television accessory to HomeKit. It is now possible to switch a paired TV on and off with Siri, however there does not seem to be a command to change the TV inputs.

Hey Siri, switch TV on/off is fine

Hey Siri, set TV input to ABC (where the TV has an Input with an input labeled ABC) does not work. Neither does "Set TV channel to ABC"

It doesn't understand input or channel.

I am able to control inputs with Siri by creating multiple scenes, like 'Watch ABC" with the TV added and the input set correctly., however there ought to be a command phrase to do that without having to create a scene for each TV input. Has anyone worked out the phrase ?