Computers have private and public IP addresses and the public one is to your Internet service provider (ISP), usually listed in a nearby city, not to your physical computer.

That ISP then has a private address that it uses to route traffic to you, individually. 

Using a VPN or similar simply moves the knowledge of the traffic source from your ISP to your VPN provider. You have to reveal your traffic source to someone, otherwise the traffic can't be transmitted. 

 An alternative to using a VPN, within Nostr, is using a caching or broadcasting relay. Then you only reveal your public IP address to them, and they pass your events on using their public IP address.

Using a VPN is most useful if it is very trustworthy, you use it always and everywhere, and you have never posted any information that might reveal the region you live in.