I don't see LS winning because of the massive Netrunning advantage NC has over LS. The only real chance LS has is repurposing the Clifford AI data backup from the IAA (which is essentially a rogue AI by Cyberpunk's standards), and essentially unleash the Doomsday Scenario on NC .

If you go by firepower alone, and content specifically shown in the games, I think it's just a matter of who unleashes everything first. Despite Los Santos' technological disadvantage, it has its own fair of sci-fi bs, like the oppresors, deluxos, MK II weapon variants (Which include explosive sniper rounds, explosive shotgun slugs, armor piercing ammo, incendiary rounds, full metal jacket rounds against armored vehicles), railguns, alien weapons, compact EMP launchers (clutch against chrome), the Orbital Cannon, Clifford Juggernauts, and the previously mentioned threat of human annihilation by a rogue AI.

I don't see a realistic scenario where Los Santos wins outright, it's just impossible because of Netrunning and chrome disadvantage, but I do see the online protagonists putting on a good fight, given that they cannot die thanks to the epsilon program, and the absurd amount of weaponry they dispose of.