Jellyfin is 100% free and open-source, it may miss some features but nothing behind a paywall. We made the choice of open-source over features (I can understand people going with plex, but I'm happy with jf)

Right. I understand now, I've not used Netflix in 7 years. Yeah you have the user login screen before entering the password. I guess there's a workaround by autodeleting cookies but you'd have to re-enter the password (and it's not doable easily by grandma)

You have a login screen with all users showing with their profile picture. For a while now. You can even make it look Netflix-like with Skin Manager plugin. And there's Quick Connect but it's for people already connected on another device.