Very simple! I would just wrap my legs around the shot line.Or, how about holding an anchor line in a ripping current, deploying an SMB to alert the boat to an emergency, and sharing air with a buddy (or holding onto an unresponsive buddy)? If you want to check your tank pressure, would you rather unclip an SPG, hold it up (with your 3rd hand), then clip it off again? Or glance at your wrist?
BTW, how would you shot the smb with one hand? It is not rocket science.
I don't need AI or any tec computer for diving.