Mac storage basics · Apps and macOS itself
Can Mac apps run from an external drive?
Short answer: Many self-contained apps run from an external drive while it's connected, but apps with system components or self-updaters can break if just dragged. Storage Studio checks which are safe.
Many can. Self-contained apps usually run fine from another drive as long as it's connected. Some don't: apps that install system components, expect to be in Applications to update, or are protected installs may break or stop updating when simply dragged elsewhere.
Storage Studio's Apps window checks each app and only offers to move ones that are safe to move, leaving a link in Applications so Launchpad, Spotlight and the Dock still open it. See moving apps.