Pets in a rooftop tent are of course no problem. However, you will have to lift up your dog or cat yourself. And please note that you should never leave a pet alone in a tent. The sharp claws and teeth can easily penetrate your tent cloth, sleeping bag or mattress.
If you prefer not to have your pet on top of the roof tent but close by, an under tent is certainly an option. Under-tents are 100% lockable and available in different heights.
