yeah... I found a button above the main door, but only for spawning friendly NPCs

there are several buttons outside the map for spawning different NPCs, but there does not seem to be any inside the map which spawn them.

it's not a bug behind the forest and silo theres a button to spawn the patrol strider and over the hill trees theres 3 buttons gunship dropship carrier and strider i might add sceenshots there tho
here this might help http://psteamcommunity.yuanyoumao.com/workshop/filedetails/discussion/943099173/1354868867722833114/

ah i see, are there any plans to have a button that does not require to noclip out of the map to activate?

Yeah But in a secret Wall you Can go in too