I am asking about specific steps (instruction) for the end user so that he can run your image.
An important fundamental difference between TV boxes (by the term TV box I mean all devices with built-in u-boot on eMMC or SPI) from the old variants of SBC , in the principles of starting the system. Khadas products belong to the category of TV boxes, with all the ensuing consequences in the development of systems for them. Again, how do you plan to run the system on Khadas products with AML chips (VIM 1 2 3)?
By the way, the built-in u-boot gives a unique opportunity to use the TV boxes as a normal PC with the launch of the system from USB media. Given that modern chips support USB 3.0, which is significantly faster than SD cards, the use of USB to host the entire system is an important element. The ease of use of USB is many times higher than SD cards.