Is it possible to get the RAW picture when it has been edited inside Photos app?
No matter what i do ios will provide the edited jpeg/heic version instead of the underlying .dng file
I’ve tried myself a little bit and unfortunately I got the same result as you.
Though a workaround might be to clone the photo in the photos app and remove all edits from the clone. Then you get the .dng file when you import the clone.