If you are talking about the shared photos or album, you can set the permission to 'Can View' only to achieve this and have no one else edit your shared photos or album.
If you are looking for something that can block/lock your images from editing or changing the Metadata, then I am afraid there is no way of doing that as of now.
Having said that, there are ways you can either revert back to original if you don't like your edits or go to versions for settings the state to that of what you desire.
If you wish to export your photo or video, you can always do so as original which will not include any of the edits and metadata that you may have added/changed.
Is there a particular workflow that you are having issues with which the non-destructive nature of this app does not take care of? If you could give more details on the scenario or problem you are encountering, we might be able to help you further.
Hope this answers your query. Please feel free to reach out if you have more questions.
Thanks. The particular case that comes to mind is when I (or family members) are viewing photos on my iPad, and accidentally hit Reject or change the star rating without realizing it. It'd be nice to have a way to prevent such changes.
As of now we have no way of locking the photo/video from being touched/edited. For any accidental changes, while you are in the loupe session, there is undo/redo action on the top bar.
Neverthesless, I will create a ticket for a feature request and see if this can be implemented in any way in future.