10 ft ceilings means at least 11 feet from floor level to floor level and could be much more
yeah it would make for a long stair obscenely long with a straight landing half way up with less than 6" risers and 12 inch treads. still long even with an inch of tuck under for the treads.
9in x9in stairs are steep but if my Aunt could still climb them into her 80s before needing a hand rail it couldn't have been too bad.