Get On-Screen Content is another action adopted from Automator, where it’s been possible to grab what’s currently shown on your Mac and do things like grab the URL from the window to use in your workflow.
Now, as part of Shortcuts on iPhone and iPad, it seems to provide the same functionality, also comparable to the Siri feature where you say “Remind me about this” and it puts the URL into a reminder for you.
I haven’t had much change to test this, especially since it’s a bit odd to figure out because it requires being activated in another app, but it seems like it provides a way for Shortcuts users to grab links and files from within specific parts of other apps and take advantage of those in their shortcuts.
If this does tap into developer APIs like NSUserActivity, I’d be curious if this action could function as a “Get deep link from this app” tool for grabbing URLs back into sections of an app (like for Things, they provide things://show?id=XXX) – if so, that’d be yet another powerful way for Shortcuts users to automate their devices.
But even as such, Get On-Screen Content is a great way to activate shortcuts that can interact with an app that’s already open (especially via Siri).