The topic of inflating a drysuit when you go Out of Air (OOA)
You are neutrally buoyant while running out of gas.
Hence, there is no need to inflate the suit.
If you are sinking, and out of air, and without an orally inflatable BCD/wing, then the only thing I can say to you is: "we all have to die some day". And, by the way, how would you inflate a suit without any breathing gas?