How can I get the "Additional Drivers" tab to show up in Settings? This is all I see?
I know it is using non-free drivers, like for my wifi, because I had to use the firmware netinstall when it complained that it needed non-free.
AFAIK the "Additional Drivers" tab of the software-properties-gtk tool is an Ubuntu thing and doesn't exist in Debian (see https://packages.ubuntu.com/eoan/software-properties-gtk and its dependency to ubuntu-drivers-common).
If you know what you're looking for, you can use synaptic and browse the "non-free" sections.