I know this technically counts as a vehicle in-game, but still these mechs have weapons. So this is a loophole.
Starbound has already introduced mechs in its 1.3 update. But this mod which has been around since 2014 and has now been updated to work on 1.3. In comparison to the 1.3 mechs, some of these mechs are massive and include powerful weapons like rail guns or rocket launchers.
For more on mechs, check out our complete guide to building and using mechs in Starbound.