VPN is not an anti-virus program. Also, you can't really backup your online accounts and restore them in case they are hacked.
6.1.5, I don't have it. This post says that the feature is only available for wayland sessions, so that explains it.
It depends on what you count as an old phone. It's Galaxy S10 in this case, it'll probably stop receiving updates soon.
You can't lie to a cat, this shit is serious.