@Yash001 See https://doc.qt.io/qt-5/qtquick-debugging.html
"what is actual text of DQT_QML_DEBUG?" - there is no text.
-DQT_QML_DEBUG sets QT_QML_DEBUG define (such defines can be checked in C/C++ code using #ifdef QT_QML_DEBUG).
QT_QML_DEBUG activates "QML Debugging Infrastructure".
I'm no expert but as far as i know, there is static and static. First static is static Qt-Libs second static is a real static standalone executable file.
If you want a real standalone executable you have to get a static version of all dependencies ".a" files not ".so". And you have to add some magic to the compiler -static -static-libgcc -static-libstdc++ (add in the Qt source to qtbase/mkspecs/linux-g++/qmake.conf) and if you want to use any kind of networking, you may also need static nss https://github.com/nss-dev/nss (some Linux versions still got static nss avaliable over packed managers).
And even if you don't use networking in your app, some other libs may include networking even if you don't use it in your code directly.