Not sure I understand why you're having so much trouble. It's literally two commands:
$ python3 -m venv venv # Create virtualenv
$ ./venv/bin/pip install pygments
However! One unfortunate thing with this is that `python3 -m venv` doesn't include the 'wheel' package in the virtualenv out-of-the-box. So it's often a good idea to install/upgrade pip, setuptools and wheel after creating the virtualenv: $ ./venv/bin/pip install -U pip setuptools wheel