Would an android device pass the boot screen/enter recovery without build.prop? Is it possible to start up an android device without build.prop? Is it even possible to use stock recovery without build.prop?
Yes, you can boot into recovery without build.prop. You can, in fact, boot into recovery without anything in /system (actually, recovery and bootloader are the only things you can boot into without anything in your /system.); build.prop and /system are only used when the ROM is loaded.