Thanks for all the response. I’m leaning toward the rolling stairs idea as it’s cheaper and safer.
Rolling stairs are made so you stay at the top. Look at the handrail. If you got something with enough steps (probably 8), not only will the floor footprint be huge (picture the size of the ones they have at Home Depot), but you'll trip over the railing trying to step off the top into the loft. They're not made like the ones you see at an airport.
I built a "library" ladder using cast aluminum steps I got from Rockler, but from my own bespoke plans. It was expensive, but not as ungodly expensive as the complete kit, and I was then able to build it using 5/4 sides instead of 3/4.
You can build your own ladder, but there's a lot of work involved. With wooden treads, each step needs to be dadod into the rails at the proper angle, and each wooden tread needs a steel tension rod to keep the rails from separating. By buying metal treads, I cut out a lot of work, and it came out beautiful.