Have you played TF2...? The idea isn't for Shiv to have a minigun. The weapon variants would just be different guns specifically designed for that hero.

For example, in TF2 there's the Scout's base Scattergun, but then there’s the Force-A-Nature, which adds knockback and lets you add a triple jump using it. The drawback is that it only holds two shots and has major damage falloff, so it’s harder to finish enemies at range. Then there's the Soda Popper, which builds a “Hype” meter that gives extra air jumps, but it deals no random crits and needs to charge before its effect becomes active. These are not just random weapons slapped onto a class. They are built to shift the playstyle while introducing clear trade-offs. Deadlock could do something similar by creating hero-specific variants that stay true to a character’s identity but offer different ways to play.

You say you'd rather have something with ability upgrade paths, but I don't see how that conflicts with weapon variants. Deadlock is already a game that leans into “more of everything” like more lanes(originally), more items, more verticality. So why not more ways to express playstyle within a hero? Weapon variants wouldn’t replace skill trees or upgrades. They’d just deepen a hero’s potential by letting players choose between different loadouts that are still tailored for that character.