The sign up requirement is a red flag with most of them, if it is asking for an account it has already missed the point. Ad overload is the other issue, some are basically unusable because of it and you end up worse off than just making an account. Been using Insta Story Viewer and it avoids both, public accounts load cleanly with just a username and nothing else is needed from you. Stories come up current and complete, same as viewing them inside the app. Reliable enough that I have not needed to look for or try anything else since finding it