There are implications for fitting over hair that mostly manifest as speed and number of uses before needing to replace parts.

Its possible but there are so many hygiene related reasoning to have soldiers shave that there is no point.

But also the real reason soldiers shave is conformity and indoctrination. Same as the approved haircut list.

To elaborate /clarify. Engineer the capability. The guy just back from leave deserves to survive a gas attack. But still mandate shaving/nair.