Add a new building item: A front door.
Placing a front door on a foundation disallows attaching items that could be used for griefing. You’d be able to place railings, foundation steps, pillars and ceilings, but would disallow building griefing items like half blocks, walls etc.
A front door used in conjunction with the tool cupboard would still allow people to take over your house should they break in and find the cupboard, but would make it more costly to grief your house.
Sure, they could blow down your front door using c-4, but the front door would be reinforced making it expensive to actually blow down. The front door upgrades along with your house just like the standard interior doors, but the front door has an added strength buff.
A front door could be a complete alternative the the tool cupboard as well. It could have a similar principle as the cupboard; whoever builds it and enters the door code has demolishing privileges, but there would be no “building blocked” area. Anyone can build next to or onto your base like in legacy, but the person that owns the front door can easily demolish anything added by other players. Only 1 front door can be placed on any attached foundation.
To take over someone’s building, you’d have to destroy their front door otherwise the current owner would still retain demolishing privileges.