Did you see this thread?
I’m a fan of the company StringSwing but they don’t make anything specifically marketed for shamisen. It’s possible that their horizontal holders for acoustic guitar or banjo hangers might fit a Tsugaru shamisen. If you email the company with the measurements of your shamisen they could give a definitive answer. Or maybe they’ll introduce a shamisen specific hanger if there is enough interest.
The ukulele hanger (CC01UK) fits the sao of the ShamiBuddy (Chuzao, 28mm wide) but I need to see if there’s enough clearance for the Size 2 shamisen dou (nagauta). I’m sure a ukulele hanger with a 2" stem (for example: CC03F2) would work for this size.