It's sort of open. https://developer.apple.com/sirikit/ https://developer.apple.com/sirikit/ Basically, it looks like you can extend Siri in a few different w

It's sort of open. https://developer.apple.com/sirikit/ https://developer.apple.com/sirikit/ Basically, it looks like you can extend Siri in a few different ways, just like extensions last year. I expect that it will open up as time goes on. The API reference documentation is linked to at the bottom of the page.