I think the "classic" stand was made and/or provided by Hohner for their electronic instruments in accordion form that used the bellows
position as a volume control, namely Electravox and Electronium. Those were electronic (not digital) instruments, meaning that they produced organ-like continuous sounds using electronic oscillators, not sound samples from real instruments. Their bellows were purely decorative and you could have sliced them open without making a difference to the sound: only the position of the bellows mattered, not any pressure inside.
So putting those things on stands actually gave you better volume/expression control rather than worse.
The stands were absurdly heavy.
I think K&M produced/produces similar stands these days. Then there is some kind of stand possibly developed in cooperation with and certainly hyped by Pigini Germany (namely Heinz Aumüller), called
Swing-Lift that is supposed to retain more control than the traditional stand. I have not heard any experiences I think or seen any videos of anybody actually using it.
Then there are strap systems of varying complexity that are supposed to better distribute the weight particularly for standing/walking players than the normal straps. There is some more variety with those than with stands, so presumably they work/sell better.
All in all, it is rare to see any of the non-standard support systems in use. Whether that means that their benefits are limited, their pricing is excessive, or people would rather tough it out, I don't know.
