I worked at a company that made POS terminals on the OS development team. We had a proprietary OS based loosely on UNIX that was ~100KLOC (kernel). It was large

I worked at a company that made POS terminals on the OS development team. We had a proprietary OS based loosely on UNIX that was ~100KLOC (kernel). It was largely designed by 3-4 core developers and maintained by ~12 embedded software engineers (in addition to drivers, apps, UI, etc).