https://www.resetera.com/threads/ps5-has-664-gb-usable-storage-astros-playroom-2-4-gb.299723/Pretty good, OS is indeed still smaller than xbox then (by 24GB). 138GB storage difference between the two, that's two big games. Not too bad.
Also I guess all the OS leaks are real, so 20 seconds cold boot matching xbox seems to be correct as well. Was expecting better.