Buster sources.list example

# apt install apt-transport-https 
deb https://deb.debian.org/debian/ buster main contrib non-free
deb-src https://deb.debian.org/debian/ buster main contrib non-free

deb https://deb.debian.org/debian/ buster-updates main contrib non-free
deb-src https://deb.debian.org/debian/ buster-updates main contrib non-free

deb https://deb.debian.org/debian/ buster-proposed-updates main contrib non-free
deb-src https://deb.debian.org/debian/ buster-proposed-updates main contrib non-free

# not sure if this two are needed (they seem to work with http)
#deb http://security.debian.org/ buster/updates main contrib non-free
#deb-src http://security.debian.org/ buster/updates main contrib non-free

# backports
deb https://deb.debian.org/debian buster-backports main contrib non-free

# virtualbox
deb [ arch=amd64 ] https://download.virtualbox.org/virtualbox/debian bionic contrib

# ---
# disabled:
#kivy https://kivy.org/doc/stable/installation/installation-linux.html
#deb https://ppa.launchpad.net/kivy-team/kivy/ubuntu xenial main
#deb https://gitlab.com/paulcarroty/vscodium-deb-rpm-repo/raw/repos/debs/ vscodium main