they could be fired from the cheek, forehead, center of chest,forearm mounted, etc.All the above were used for firearms at one point, with varying levels of success, but usually failed for packaging and recoil reasons.No reason an airgun needs to look like a firearm.
An air cane intended to be fired from the cheek,for instance, could have a tiny ghost ring and spur trigger that were folded under a sliding ferule near the grip...the only clue beforehand would be a tiny bead near the tip of the cane.
Or take the free pistol concept a step further....allow the grip extension to contact the forearm, supporting the wrist (or even elbow)taking all the wrist muscles out of the accuracy equation. You could even start the barrel back at the shoulder..it wouldn't look like a gun (at least not one from this timeline...
)but it might look very good, and certainly out of the box