What parent is saying is that even if you have the file and can relink to the application .o, you can't submit your own version of an iOS app that's already on

What parent is saying is that even if you have the file and can relink to the application .o, you can't submit your own version of an iOS app that's already on the App Store. There's literally no way to use LGPL Qt on iOS. Thankfully Qt considers iOS a "mobile device" and not an "embedded device" so you can deploy a Qt app through the App Store with a single deployment license and not a per-unit royalty.