Yes, but only 'well written ones'. Anything that decided to hit the hardware directly from DOS, or did something that OS/2 didn't support in windows just crash

Yes, but only 'well written ones'. Anything that decided to hit the hardware directly from DOS, or did something that OS/2 didn't support in windows just crashed or had undefined behaviour. Even windows in protected mode couldn't do all DOS things any more. Even if you dropped out of protected mode, and fiddled around too much you'd end up breaking windows when you switched back to it. Back then you'd have all manner of weird DRM schemes which used dongles on the parallel port, not to mention manually set IRQs, I/O Ports and blocks of high mem (between 640K and 1M) where your device drivers were baked into the DOS application, NOT the operating system. There were some driver.sys type drivers for random hardware, but mostly it was just cheaper to write the driver inside the app itself. Programming under DOS was more akin to writing to an Arduino rather than linux/windows back then.