Note: I know that the code of the stock camera app is behaving incorrectly. It should not invoke com.android.camera.action.REVIEW Intent but Intent.ACTION_VIEW. At least this is what Open Camera does in its openGallery() function, plus a few other stuff.
Camera (including OpenCamera) does not open gallery.
Both Camera and OpenCamera are using com.android.camera.action.REVIEW intent after clicking just taken picture (right bottom corner) to review taken picture
com.android.camera.action.REVIEW is missing from Gallery Manifest.
Editing intent (using interceptor from AppManager) to android.intent.action.view brings choice of galley (and other apps too)