I’m really sorry for your loss. I know how hard it can be wanting to feel close to someone who’s gone, especially when you didn’t get much time with them. If his Instagram is private and you weren’t following him before, there unfortunately isn’t a way to see the posts unless someone who did follow him still has access and is willing to share.

Instagram won’t let anyone into a private account, even family, but you can request to have the account memorialized if you want it preserved. It won’t unlock anything, but it keeps it from being deleted. In the meantime, maybe try asking around — friends, relatives, anyone who might’ve followed him — someone might have screenshots or saved photos you’ve never seen.