@f_dion@synths USB is asymmetric. The "B" device is a peripheral and the "A" device is a host. Bs can't talk to Bs directly, and As can't talk to As. (USB OTG and USB-C change those rules.)
Anyway. the keytar is just a "Vortex Wireless 2". It does have a 5 pin DIN MIDI out port. So I could hook it up to any of my hardware synths. Hadn't really considered that.