I made a data pack that adds tanks that can be created by building them, crafting the custom engine, fuel, and ammo, and activating the tank with the engine. When the player gets in the tank, his hot bar is saved and replaced by the tank controls for driving and adjusting the barrel. Dropping any controls will fire the tank, and tanks can blow up blocks and also shoot and destroy each other. The tank has proper gravity and hitboxes, although a few bugs relating to movement may occur.
Here is my full showcase: