I really want to try #Debian. My impression is that it's a little bit harder than #Ubuntu and Ubuntu-based distros (I'm using #pop_os).
If I switch to Debian, what will I miss from Pop_OS?
Discussion
I haven't used Pop_OS but have been a long-time Debian user who migrated from Ubuntu to Debian. You'll probably lose bundled Nvidia drivers (if you use Pop_OS for Nvidia) and you'll be given a more bare bones default installation.
Otherwise, as long as you don't mind a slightly more techy install process (Debian focuses on universal compatibility over ease of use with it's installer) and a more bare bones default software selection you'll be able to do just about anything you can with any Debian derivatives. Same commands and most if the same software (minus the Cosmic desktop AFAIK) should be available to you right out the gate. KDE and GNOME both offer very GUI focused setups such as a GUI software store.
