man pacman
Some options:
d, --deps
Restrict or filter output to packages installed as dependencies. This option can be combined with -t for listing real orphans - packages that were
installed as dependencies but are no longer required by any installed package.
-e, --explicit
Restrict or filter output to explicitly installed packages. This option can be combined with -t to list explicitly installed packages that are not
required by any other package.
So one option to list:
pacman -Qdt