I can see issues with mechanical keyboard instruments. But why bother hauling an acoustic piano up there when there are electronic keyboards that are smaller, lighter, and can duplicate the sound and/or many other instruments? They’d have to find a workaround for any pedals (volume, sustain, leslie, etc. , I suspect.
Brass, violins, violas, and woodwinds? I think it’d be easier as they won’t have to support the weight. A bass or bari sax in gravity probably put some weight on the players’ neck from that strap.
Lots of issues with a drum kit. In G, cymbals rest on felt pads and wing nuts keep them from flying off. In zero G, they’d be often contacting the wing nut. That’s not going to help the tone. And the at rest angle of the cymbals would be constantly changing. You can’t really clamp those down without muffling them. The whole set would need to be secured to something and the drummer would have to belt in to her seat. The clamp for the snare would have to be tightened more.
Strings? I can’t see how gravity or lack of G would effect fretting/fingerboarding or picking, strumming, or bowing. Holding or positioning the instrument would be the issue. Upright bass? It’d have to be fixed in position and maybe some foot clamps for the player. Cello? Do players just place them between their knees or hold them with their knees? I guess put the leg thing in a ball joint fixed to a surface with the seat and strap the player in. Guitars, mandolins, banjos and instruments of that type would be an issue. They’re usually played either hanging from a strap or resting on your thighs. Yeah, you could hold the body against your chest with the palm of your picking/strumming hand but that could limit your playing. They’d have to come up with an alternative type of strap. I remember years ago seeing a strap in a catalog that was a wide belt, a plug (I guess you’d call it), and an adjustable harness for the strap buttons on the instrument with a socket in the middle. The idea was, put the belt on around your waist with the plug in front, put the harness on the guitar with the socket in back, put the plug in the socket and you could play the guitar and do windmill spins with it too. ZZ Top may use these. For smaller instruments (ukes and mandolins) you might have to put the belt around your chest.
That would work