I am developing cross-platform Qt application. It is freeware though not open-source. Therefore I want to distribute it as a compiled binary.
On windows there is no
The probably easiest way to create a Qt application package on Linux is probably linuxdeployqt. It collects all required files and lets you build an AppImage which runs on most Linux distributions.
Make sure you build the application on the oldest still-supported Ubuntu LTS release so your AppImage can be listed on AppImageHub.