actually the weakest link of the main door is the lock. Apartment doors are already fire rated and it’s quite tough. If there’s a space there between the door and the place to install grill then do it so can put shoes there. Otherwise no need grill just install a good digital lock and use long screws for the strike plate.

High floor don’t need window grill unless you have children. If the thief want to Spider-Man in then let him, buy home insurance. You don’t want to feel like living in a jail cell. And always remember, most of the time it is inside job.