I actually haven’t gotten my metal tube yet. It’s only two ships away! But to the game’s credit, you don’t have to take the crappy pistol if you don’t want to. There’s a sort of shotgun you get quickly, but the problem is keeping enough ammo for it. Then there’s a third gun that I can’t figure out because it takes too long to charge up? I think I’m just not doing something right, and because it’s a rogue-like-ish, I’m reluctant to experiment too much. You also have a grenade slot with a few options, and even a utility slot that can do things to manage enemies.
So even if the gun doesn’t get better, it’s not like it’s your only option.
There’s an active Void Bastards thread where they probably talk in more detail about the stuff that unlocks, but I’ve decided to avoid it because I like how the game is revealing stuff gradually. For the time being, I’m happy to just bide my time and see where it goes.