Shortcuts are now managed entirely in the Shortcuts app. These can work on their own to create/find/append Day One entries or may connected with other apps as well. Details about using Shortcuts on Apple’s help site here.
Some users have created Shortcuts combining other apps to add data to their journals in Day One. Some of these may require additional services or other 3rd party apps. These are not officially supported by Day One.
Moods in Day One.
Save Quotes from Overcast podcast in Day One
Ideas for journaling with young children by Dylan (requires Toolbox Pro)
Daily Day One Entry (with randomized prompts)