Can you switch to 3.5 touchscreen and HDMI screen too without any trouble on a Pironman 5?
No.
If you connect both the 3.5-inch touchscreen and the HDMI screen at the same time, only the HDMI screen will display.
If you first connect the 3.5-inch touchscreen and successfully boot the system, then connect the HDMI screen, the HDMI screen will not display anything.