As I understand it, those Slack/Uber/Skype Siri widgets are opt-in by the developer and it is the developer who needs to write those. The same goes today for sh

As I understand it, those Slack/Uber/Skype Siri widgets are opt-in by the developer and it is the developer who needs to write those. The same goes today for sharing extensions and notification center widgets. So Apple is not bypassing vendor's app per se, it just provides a way to not launch whole app UI when it's not required, but it's the developer who is still in control.