Thank you Jeremy. 

I am currently quite confused. Since I'm going the bullseye-path shouldn't I use the bullseye-repos?

This is what I have currently for my security.sources.list:

[signed-by=/usr/share/keyrings/tkl-buster-security.gpg] http://archive.turnkeylinux.org/debian bullseye-security main
deb http://security.debian.org/ bullseye-security main
deb http://security.debian.org/ bullseye-security contrib
#deb http://security.debian.org/ buster/updates non-free 

This is my sources.list:

[signed-by=/usr/share/keyrings/tkl-buster-main.gpg] http://archive.turnkeylinux.org/debian bullseye main
deb http://deb.debian.org/debian bullseye main
deb http://deb.debian.org/debian bullseye contrib
#deb http://deb.debian.org/debian buster non-free

When I try to run your script it just gives me an error

./keyimport.sh: 4: Syntax error: "(" unexpected

Thanks!