Vehicle combat needs to be balanced
Hot take, ranged boss attacks should not one-shot vehicles. Two shot? Maybe. Three shot? Probably. We've got cannons and all kinds of fun stuff, but a single ranged boss attack will turn any tank, boat, or flying machine into a cloud of parts instantly.
The offensive ability is lacking as well. The cost of cannon balls is way too expensive for the damage output. You need a dozen cannon shots to take down a brute, but it only needs one shot to turn your vehicle into dust. Using the cannons on small enemies is horrible as well, with many enemies surviving one or more hits! These things aren't cheap!
At least give us armor pieces or something so that we can attempt to use this stuff in fights! Let us add the poison jars or potions to cannons so we can deal damage over time while strafing or heal allies with a mounted slurp bombardment. Give us a shield bubble powered by energy so we can have proper tanks. Anything to make vehicles more than a fun trinket! I'd settle for just massively reduced damage to vehicle parts at this point.
Rant over :)