This question has aged a little but maybe this helps others:
I had the same problem with parallels on a MacBook Pro M1. After running the script to convert Debian to DietPi (Generic) no network adapters where found. The problem is, that DietPi is expecting an eth0 network interface, but mine was labeled enp0s5.
To find the name of your card please enter “dmesg | grep -i eth”.
My outpout was “virtio_net virtio1 enp0s5; renamed from eth0”
Now edit “/etc/network/interfaces” and add “rename enp0s5=eth0” before the #Ethernet section.
(replace enp0s5 with the name of your card)
After a reboot everything worked for me.
-Olly