This app was mentioned in 1 comment, with an average of 9.00 upvotes
Woah, woah. LGPL is not "free for commercial usage". It requires you to allow the user to use your app with a different version of the LGPL code. You can't statically link to Qt, you have to use dynamic linking and allow the user to use a different shared library.
Now, tell me, how do you do that on iOS or Android when the app is signed and sealed? There is Ministro on Android, enabling shared libraries. but try telling your user "ThisApp requires additional libraries, download from Google Play" and a lot of them will uninstall right away. I don't even know how could you do it on iOS, never used it.
Anyway, what I'm saying is that it's not so straightforward to use LGPL on mobile.