Honestly, if someone posts a story on Instagram, they have a right to know who’s viewed it. Trying to bypass those “seen by” notifications is basically sneaking around someone’s privacy. If they wanted you to see their story anonymously, Instagram would make that possible.
Maybe you should just respect their privacy and boundaries instead of looking for ways to go behind their back. Social platforms have these notifications for a reason—to encourage transparency and consent. If you aren’t comfortable with them knowing you viewed their story, perhaps it’s best not to view it at all.