Technical explanation:
iOS apps cannot add systemwide actions in context menus, like for text selection. At best, they can create a sharing extension to have their app shown in the share sheet (page where you select who you send something to) and potentially add an action for easier discovery.
The only place they can add a systemwide actions is in their own app, hence why only the ChatGPT app has the Ask ChatGPT action.
Technical explanation:
iOS apps cannot add systemwide actions in context menus, like for text selection. At best, they can create a sharing extension to have their app shown in the share sheet (page where you select who you send something to) and potentially add an action for easier discovery.
The only place they can add a systemwide actions is in their own app, hence why only the ChatGPT app has the Ask ChatGPT action.
When you select text, you get options like Cut/Copy/Paste, Look Up, etc. Text things.
Apps can add their own actions next to these, such as the ChatGPT app adding the Ask ChatGPT action.
The thing is, iOS does not allow custom actions to be used outside the app which added them. So the Ask ChatGPT action only appears in the ChatGPT app and nowhere else where one would benefit from a quick shortcut like that.
The action is now mostly useless if it can’t serve the purpose of being a shortcut to ChatGPT from any text selection anywhere, because once you’re in the ChatGPT app, you could just ask - shortcut not needed.