As it's often discussed that there's not much to do as a passenger, I thought we might consider the obvious one - shooting. Being able to shoot hand-weapons while seated in a passenger seat would make for interesting SV mini-gunships designs (without being too OP against HVs). It would also allow some fun while sitting on the side of a HV tank, like in Halo. Alternatively, seat some buddies with multitools for a poor man's demolition or mining crew in early game. Later in Empyrion's development when friendly AI vehicles are a thing, it's a great mechanic to have for PvE missions - get in and shoot at stuff while AI drives/flies you to next infantry location. It seems like it might be easy to implement relative to the amount of new interesting gameplay it could allow.