Do those Instagram story viewer tools actually let you watch stories anonymously?

I’ve seen a bunch of sites claiming to let you view Instagram stories without the person knowing, like just type in the username and watch from a browser. One of them was labeled as an Instagram story viewer and looked pretty straightforward, but I’m not sure how legit these things really are.

Has anyone actually tried one that works? Does it just pull public stories, or does it mess with your account in any way? I’m not trying to be creepy, just curious if they function as advertised or if they’re just sketchy clickbait.