Unfortunately, as there is no official support for VTTs from SJG. It is not permitted to build in rules text and such into the ruleset, as that's breach of copyright. You can however add this information manually to your campaigns and set it up as additional information/notes within all of the skills, attacks, spells, abilities, traits, etc on the character sheet. This does not appear when you make a roll, but there is an icon you can click to easily access this information or link in chat for others to reference. There is also facility for any modifiers you need for all those things as well. Not all attacks in the combat tab of the character sheet need be weapons either. You can setup all your hand to hand attacks, range attacks (spells, guns, powers, or whatever) all with reference info, modifiers, modes of attack, parries, etc. Pretty much any roll you need to make in GURPS has a facility for it somewhere in the character sheet. There is a link in the OP which demos how to set all this stuff up. Not sure how current it is since that was done a while ago, but it does cover the basics.
I would be happy to help to get your feet with the FG GURPS ruleset, jump onto my groups discord (
https://discord.gg/8dXSZkg) and we can try work out a time. Alternatively, all VTTs are just different tools for you to play your games, if Roll20 is working for you, then keep using that. If it ain't broke, don't fix it. :)