How long can a commercial airliner fly at 90deg roll?
What you're talking about is called "knife edge" flight, where all of the lift is coming from the sideways fuselage, making it a lifting body aircraft with big fins (the wings) sticking up and down that aren't doing anything (rolling sideways during a ballistic arc doesn't count).   The rudder is doing the job of the elevator, and the elevator is doing the job of the rudder.

To do this is requires a fairly deep fuselage profile, preferably reasonably flat sided so it makes a decent lifting body, with a really powerful rudder to effectively function as the elevator for this lifting body, and it's helpful to have a high power propeller engine on the nose helping with the lift generation.

Just about the only airplanes that meet those characteristics are purpose built aerobatic machines that can sustain knife edge flight indefinitely or some military jets.  Certainly no airliner could ever do that.