If the loop is large, you don’t have to move too fast. Fairground rides spin fast enough to exceed 1g with little kids in them, and those rides are usually not wider than 10m, often less. Speed here is distance around the circumference, so twice the radius, half the turning speed.

I don’t have the numbers in front of me, but generally it’s considered that the issue is more that if you’re standing on a spinning cylinder, you might have weird balance issues due to speed differences between head and feet. Also, you have to remember you don’t have gravity, so as you intuit, entry and exit are trickier.

Two broad ideas for entry/exit: do it at the center where the physical position is stable, then “spin up” some how, or alternately get up to external speed and lock on to something that you then elevator through the surface.