Where's the documentation for what you can do once you setup application links? The ones I can find delves into HOW to set it up, but not WHAT you can do after you set it up.
I used ngrok to expose my local testing Jira Data Center, and setup application links between it and my Jira Cloud.
Now what can I do with it?
The Cloud/DC instances don't seem to share the project list with each other. It seems the only thing I can do using application link, is to link issues from each other.
This 8-year-old ticket (https://jira.atlassian.com/browse/JSDSERVER-3746) seems to suggest the same.