Applets have a very elaborate mechanism for defining associated application URLs. It boils down to a "Open in $app" action being added to the applet's context menu.
Currently there are only two first-party applets making use of it:
- The weather applet gives a link to the weather data provider. However it's a bit broken and not very useful. https://invent.kde.org/plasma/kdeplasma-addons/-/merge_requests/101 proposes to remove it
- Folder view uses it to open the folder in a file manager
Given that it's effectively unused and the folder view case can likely be implemented much simpler I propose to remove the whole infrastructure, making plasma-framework a tiny bit leaner