This is also something I would love to know. It’s not only the share sheet, also the Camera buttons (which are “Cancel” instead of “Abbrechen” for me. I also posted a thread but haven’t received anything so far.) I’ll check out your suggestion too!
I think, it has to be "CFBundleDevelopmentRegion": "de"
When I set this in a bare XCode project, my labels and buttons are german. Not working in Expo right now, I will build a simulator build and report back!
So, I added:
"CFBundleAllowMixedLocalizations": true,
"CFBundleDevelopmentRegion": "de"
And now it’s working perfectly 