Android 7.1 might be under testing for Samsung devices
On the other hand, however, this is not at all a confirmation that there's anything under testing at the moment – it could be just that the development teams behind these apps would prefer to be ahead of the curve and futureproof their code so they don't have to do it at a later date. And in Samsung Health's case, the app is also available to non-Samsung devices as well, and Samsung could simply want to maximize compatibility rather than risk having unforeseen bugs appear on newer versions of Android.
However, it's almost a given that there will, at some point, be an official Samsung update to 7.1 – Android O, the next major version of the OS, is months away, and it's highly unlikely Sammy will keep its users on an outdated release until then. SamMobile goes as far as theorizing that 7.1 could come together with the Galaxy S8's official release, but for now, we would advise against getting one's hopes up too early.
Things that are NOT allowed: