Hey! Been there - did competitive analysis for a startup last year and definitely didn't want our brand account showing up in competitors' viewer lists. Felt like I was sneaking around haha.
So
Viewverio worked well for me when I needed to check out what other companies were posting without leaving footprints. You can browse profiles and content without actually viewing through your account, which keeps things discreet for research purposes.
One thing though - it won't show you private accounts or let you interact with anything (obviously, since you're not logged in). For stories specifically, you'd need to catch them while they're up since they disappear after 24hrs.
Pro tip from my experience: also just follow them from a burner personal account with a generic name. Sometimes the passive scrolling gives you better insight than active stalking anyway. Good luck with your research!