Some dogs can do the duel role but you need to make so they can monitor flock from inside home and be above go in and out of house through a doggie door. This means an additional level of training and house would get messed. Most dogs kept indoors as pets will not be as invested in protecting property hence the need for training. A big advantage that can be realized with dogs accessing house is they can inform you of problems they can not handle. We occasionally tree coons or catch one in the live trap so one of my dogs comes in and does the Lassie thing to bring me out. That is better than dogs wearing themselves out going after something they cannot reach or ultimately tearing up teeth trying.
Many of the mollosar type LGD's are well suited for cold but heat can be more problematic.