On Mac, you could make a little Shortcut that accepts your text selection or maybe even a screenshot and sends it to AnkiConnect to make a new note. Add this Shortcut to your share sheet and you can create new notes from any app. Later, go over the notes in Anki and add questions or if really lazy send the backsides to an LLM to create those questions.
Now I wanted it for myself and just made it. So at least I can confirm this works.
Only difference is I don´t actually use the sharesheet much so I do it with clipboard content: Step 1. Take screenshot or copy text. Step 2. Make a request to AnkiConnect and have it create a new card with clipboard in Anki.
Works flawlessly on Mac/Desktop but if you want to do it from mobile devices, you have to muck around with network permissions. Too much for this evening but this alone opens up possibilities.
Thanks for the stimulating question! :)
Thank you - I hadn't considered this.