Although this question has already been asked a few times before (without hardware, nvidia-settings), either the question was not answered clearly, or it relied upon a graphics card that is not available on systems such as my own. Is there a way to calibrate the color profile in Ubuntu without a GPU or colorimeter?
Hmm. You can use displaycal-gui to create a synthetic ICC profile, then either double click the .icc file to install it or use the Profile Loader bundled with the application.
However, displaycal-gui doesn't let you edit curves of your color profile as far as I know. You'll be using something like this: