This GUI isn’t super intuitive but heres where to click to dig down in and find your settings.
UDM > Settings (Bottom of sidebar menu) > Advanced > SSH
UDM > Network > Settings (Bottom of sidebar menu) > System > Application Configuration > Device SSH Authentication.
Lots of poor documentation around the interwebs for this… here is the required packages to make this useful. If you want the normal driver with xorg just remove headless from the package name.
apt install linux-headers-$(uname -r) -y
apt install nvidia-headless-470-server nvidia-utils-470-server libnvidia-encode-470-server -y