As Sheldon explains, the 5”-screen DFR0550 from DFRobot is also using the same DSI Display Connector as the official rPi touchscreen. It is NOT connected via HDMI! Also the number of pixels is identical: 800x480.
So I was convinced that it would work with RoPieee without any necessary adaptation. But it turned out otherwise. The touchscreen is reacting inversed, compared to the official rPi 7” touchscreen. If you want to put the music on hold, you don’t have to push on the pause button, but you have to push somewhere in the middle of the top of the album.
To fix that inconvenience behavior, I found out that you have to change the setting “lcd_rotate” from “2” to “0” and reboot RoPieee. The setting is in the file /boot/config.txt . After rebooting RoPieee, also the touchscreen is reacting in a correct way.
So now the 5” screen is reacting exactly like the official 7” screen, but is just a lot smaller (121mm x 65mm) compared with the official 7” screen (193mm x 111mm).