Fantastic update. Looking forward to further developments. 120mm cannon feels a little on the weaker side of things currently. It's susceptible to hitting buildings and cars and such like other weapons, but doesn't have the ability to rapidly follow through like other weapons - it takes more skill to use, but it doesn't feel particularly more rewarding. I'd much rather take any of the autocannons than the 120 because they let me take far more fights (with way less risk of blowing myself up) while sacrificing what feels to be a negligible amount of DPS.
Minor nitpick on the worldbuilding: a 5 petawatt laser drills through something like 20 kilometers of graphite a second (I think). I know it's "ultra high energy" but by the prophets it doesn't "violently ignite" or "sear a hole", it turns whatever it's looking at into a rapidly expanding cloud of ionized plasma, regardless of whether or not it's fleshy. I'm pretty sure a weapon like that would make armor irrelevant.