Either give an existing zombie type the ability to open doors, or create a new one, a more intelligent zombie creature, if you will. Of existing zombie types I was thinking maybe zombie master, necromancer, or feral predator - a type that’s relatively uncommon. Mi-go? Zombie scientist? Although scientists are kind of common. Labs might become problematic… or hilarious.
Or possibly this: For example create a copy of the child zombie monster type. Make it every bit identical, except it has the ability to open doors. Would there be conflicts? It would carry the identical name and graphic but it would certainly have different creature ID.
I suppose we should also then give the player the ability to LOCK doors…
Should doors have actual locks with broken/intact status?