pre-filled pin assignment file import procedure

Yes. I find this is 'best' done outside the tools.

Having created your project locate the '.qsf' file in the project directory. Locate the same file from the sample DE0 project you're referencing. This file contains all the settings for a project.

Copy all the 'set_instance_assignment' and 'set_location_assignment' from the DE0 settings file to your project file. This will take all the pin location assignments and appropriate I/O standards for each pin into your project.

When you now load your project into Quartus it will be expecting all the same signals and I/O standards as the DE0 project you've use as a reference.

Alternatively, you can open the DE0 project, copy it to a new location and replace any of the HDL source files with your own. You will end up with a project with all the pin assignments and pin names you need.