Hi there,
If you want to open a link in a native app instead of the browser (like opening a Twitter link in the Twitter app), you can do this in Thunkable!
Activity Starter is what the component that did this was called in older versions of Thunkable, but the general practice of opening a link in an installed app is called Deep Linking.
You can do this in Thunkable with the Open Link block from the Control drawer of blocks. This block is the same in the snap-to-position UI and the new drag-and-drop UI.
You can read more about Deep Linking in your Thunkable apps here: Deep Linking with 'Open Link' (Activity Starter Function)