Where it stops
It does not make their profile public inside Instagram. In the app, the account remains private to you.

What it does instead: it reads the hidden data back to you as one report, and you never sign in with your own account.
IgprivateviewerA lookup by username. One report back, with secret messages, profile stalkers and unfollowers.
It does not make their profile public inside Instagram. In the app, the account remains private to you.

What it does instead: it reads the hidden data back to you as one report, and you never sign in with your own account.
What do you want to find out about them?
The report carries a secret messages part for exactly that.
Profile stalkers and story obsessions show who looks at the account most.
The unfollower tracker lists the accounts that unfollowed.