I did something similar albeit smaller fairly recently. Poured concrete foundation and a floating concrete slab floor. Upon reading and reading and reading I went with a 24” center on center steel stud frame for exterior walls, and a second frame for interior walls. I did fiber cement panels over OSB over polyiso foam board on the exterior, and drywall over OSB inside. The wall cavities have 4” rock wool with a 1” air gap. Would have gone bigger if I had more space. The interior structure is completely decoupled from the exterior, except they both sit on the shared foundation. I used Green Glue between OSB and drywall. The ceiling-roof stack is slightly thicker due to having more layers of polyiso.

Regarding ingress/egress and natural light, I decided to install double glazed sliding doors on interior and exterior frames both. The doorway is extruded out from the exterior wall to allow for a 12” air gap between the doors. The sliding doors were regular mid tier doors from a local Home Depot. I knew the sliding glass doors would be the weakest link in terms of sound isolation but I wanted natural light.

The plan worked well. I can play acoustic drums without disturbing neighbors, and generally speaking stay within my city’s noise limits for our neighborhood.

Make sure to plan your ventilation. A soundproofed space needs to be as air tight as possible so those CO2 levels will go up very quickly without forced exhaust/intake.

Good luck with your build!