Thanks for porting DietPi to the Rock64!
I’m using this to setup Nextcloud on the Rock64. One nuance is that external usb drives get automounted to /media/user_name/name_of_usb_drive
Nextcloud, by default can use external drives if they are mounted to /media/name_of_drive, but cannot use drives when mounted to /media/username/name_of_drive, even if you set permissions for anyone to access it.
Maybe consider changing automount points for USB drives when / if nextcloud is used?