Most smaller satellites and other larger but simpler space craft with a less demanding mass fraction tend to use cold gas thruster, importantly with a common or as few as possible pressure vessels, however such thrusters have a tragically low performance, and as such, most lager space craft will use either monopropellant or even bipropellant thrusters. This of course comes at the cost of complexity and a larger mass fraction however. my question is, could a compromise be made between the two mechanisms, where several reaction thrusters could be pressurised from the same combustion chamber, not too dissimilar to rocket engines with multiple nozzles. What would be the practical limitations of such a system- how could the cooling of the pressurisation lines be managed?
You want to use a hot gas thruster with one combustion chamber and several selectable nozzles?
But how should the active nozzle selected? You need something like a valve with one input and as many outputs as the nozzles. But this valve would be damaged by the hot corrosive gas. Problematic for a satellite operating over several years.
Valves for the cold propellants exist for many decades and are known to be reliable. No satellite operator would trust a hot gas valve without successful history.