Possibly, however, you would need the app to specifically disable screen capture. Even so, there is no stopping someone from recording the screen from an external device, so keep it for specific use cases (ie not nudes)
Discussion
Of course, photos cannot be owned unless you keep them to yourself which makes them useless.
But this idea compared to traditional auth has these benefits:
1. You can host anywhere.
2. Data is encrypted at rest, so no leaks from unauthorized hackers.
3. You own the keys at all times, never share.
Downside would be that potentially large data is being sent back and forth from your nsec bunker server.
That is, if I understand the nsec bunker model correctly.