Hello Muhammet Aydın,
The latest BSP Release (L5.4.3_1.0.0) supports the i.MX8M Nano and there is an image based in Qt5 available. This is the only supported Qt iteration on the BSP.
It is my understanding that Boot2QT was rebranded as Qt for Device Creation.
https://doc.qt.io/QtForDeviceCreation/
You would need to port it to your desired board. However, there are some third party boards from Boundary Devices that do support this stack:
https://doc.qt.io/QtForDeviceCreation/qtdc-supported-platforms.html
I hope this information helps!
Regards,