There is a iOS.PList.UIFileSharingEnabled build property but no one that leads to a LSSupportsOpeningDocumentsInPlace plist entry. This additional one is needed for displaying files in the new iOS files app (see UIFileSharingEnabled).
Sorry, I overlooked this Build settings:
Creating a uxl file with this content:
<Extensions Backend="CPlusPlus" Condition="iOS"> <Require Xcode.Plist.Element> <![CDATA[ <key>UIFileSharingEnabled</key> <string>YES</string> <key>LSSupportsOpeningDocumentsInPlace</key> <string>YES</string> ]]> </Require> </Extensions>
will also create the necessary plist entries.