Is there any legit way to view a private Instagram account, or is that all scams?

They're all scams, every single one. A private account is private by design, there's no site or app that can bypass it, so anything claiming to is either stealing your login, running you through endless 'human verification' surveys, or installing junk. The only real way in is to follow and get accepted. Good instinct to ask first.

If a random website could open any private account on Instagram, Instagram wouldn't have private accounts. That's the whole tell.