To have a public front that is outside of the lan firewall. The idea is that you do not have to open your lan to anything. The only communication will be the encrypted wireguard tunnel between the VPS and your Newt instance.

You can run the Pangolin also on the lan, but you will need to open a few ports then on your lan firewall, and manage your ddns etc. if you do not have a fixed IP at home.

For less than 4€/month I opted for the VPS route.