Thinking about Surya finding his food made me realize that his sense of hearing is far better than his sense of smell. He's instantly on the alert when he hears the bag unzip and moves towards the sound of kibble on the floor.

My deck is on the upper floor of the house, well screened with chicken wire to prevent any disasters. I would think about setting up a tunnel in the downstairs so they could go out into a fenced off portion of the garden but my garden has gone totally wild and I've never had a lawn, and I'd be afraid of neighbor cats getting in and leaving their viruses behind.