My understanding of international law is that your treatment is dependent upon whether you are a combatant for a particular nation rather than what your nationality is. So Eagle Squadron pilots should have been treated the same as any RAF pilot. I think that’s the theory anyway but what the Nazis would have done out of expedience is probably a different matter. Towards the end of WW2 the Nazi armies contained nationalities from all over the world (including their enemy nations such as Russia, Britain, the USA and diverse places such as Tibet and India) and I imagine the fate of those troops was often a grim story if the Soviets got them but somewhat gentler if the Western Allies got them.