shortcuts-appsiri
I was testing something out, but in one of my apps I can set a voice command for a shortcut. I manage the shortcut in that app and don't use the Shortcuts App. But after I deleted the Shortcuts App those shortcuts I created in app stopped working.
I can see click the add button but Siri just says she doesn't understand.
Do I need the Shortcuts app to be able to use in app shortcuts?
Yay my first Shortcuts question!
Use the Dictate Text action.
This action will convert words you speak into to text and pass that text to the next action.
Currently, there is a bit of down side: You will not be able tell Siri in one sentence "Tell [Shortcut Trigger], Apples are cool" Instead you need to do it in two parts "[Shortcut Trigger]" wait... "Apples are cool".
Warning: Make sure to pick a language or it will silently fail.
I just tried some of my shortcuts, and they work perfectly fine on my Apple Watch.
However according to Apple:
Shortcuts that require an app to open on your iOS device might not work on HomePod and Apple Watch.
(Source: Use Siri Shortcuts)
So maybe that is the reason your shortcut works on you iPhone, but not on your Apple Watch.
Best Answer
Yes, you need the Shortcuts app to use Siri Shortcuts.
In iOS 13, Siri Shortcuts were integrated with the Shortcuts app and every Siri Shortcut is a ‘normal’ shortcut too.
See https://developer.apple.com/wwdc19/101 at exactly 1:00:00