Can You Recommend a GUI Tool for Managing My PF Rule Set?
Yes, GUI tools do exist, e.g. pfSense (FreeBSD based), PfPro (OpenBSD based and supposed to be portable)
No, this tutorial is taken in without them
Learn to understand pf.conf first, then make informed decision
Keep your pf.conf readable, already!
($EDITOR + pf.conf is faster anyway)