Welcome : )
What an adorable pair!! It will be great if they remain bonded as they mature. So you get to see lots of bunny cuddles like this.
What are age are they now? Dennis looks so little in comparison, it’s almost like Bun Franklin is an adult.
I can understand your reluctance to have a cage. I think they have plenty of room and they look to be relaxed and settled. As they mature, you may find you have to confine them a bit more as the litter habits can go south once the hormones come in! Thankfully, this is just a phase.
I think when you allow rabbits a lot of space, it’s important to provide some hiding places. As you have done with boxes. Somewhere to bolt to if they get startled.
Just be aware that boxes can be moved! You may fine a clever rabbit will use it to launch over pen sides. So something heavier would be a good addition.
Some other modifications I’d make is place the sipper bottle on one of the pen panels so there is plenty of room in the litter box. You may have to add a second litter box as they grow. Plenty of hay in the box should keep them toileting there.