When I started diving in Hilo in 1976 the Hawaiian backpack was common. About 1/2 of us used them, the others used simple plastic "cam packs", which you can still buy.
My Hawaiian backpack was commercially produced and sold in local dive shops. I cannot remember the manufacturer, but it was local based, in Honolulu I believe. Sea Horse? Not sure. I seem to remember a sticker on with the picture of a sea horse....
The version I used was a flat aluminum backplate (vaguely similar to today's aluminum BP's) and had two bent aluminum arms covered with foam... similar to some of the picture above, but a bit different. It had a single stainless steel tank band with an adjustable cam mechanism to clamp the tank in securely. I had a single waist strap.
In the water it was
not as secure as a current bp/w with Hogarthian harness, but was "secure enough". I don't remember it moving around any more than a current poodle jacket does, errr jacket BC I mean
The main attraction (for me) was the simplicity and the amazing ease in donning and doffing in the water (very useful from small boats, zodiacs, etc.).
It of course did not have a wing, and in those days we were using "safety vests" for surface floatation (they look like snorkel vests today, or somewhat like the life vests on airliners).
Mine long since bit the dust, but they were a pleasure to use.
Best wishes.