VPN

Do you mean IP spoofing? 🤔

Can they see my traffic?

Depends. It is just a VPN server, where you decide to host it is key. In other words don't set it up on your own internet connection expecting it to protect you from your own internet connection.

A VPN connection allows you to tunnel traffic to a VPN server (e.g PiVPN) so you would be using the internet of wherever you configured the PiVPN at.

Also see their own description

To us, the next logical step here is also ensuring the pipe you are using is as secure as possible. This not only could include unknown networks at airports, Starbucks, generic public hot-spots; but also your ISP. To that end, We'd like to make sure these scripts also work on a Debian image from an Amazon free tier server.

So say you are at a public hot-spot and want to secure your internet usage there, in this case you can tunnel your internet usage to your PiVPN sitting at home & use your home's ISP connection.

Or as they say you could configure their software on a server hosted elsewhere (e.g. Amazon services) & this way you can use the internet there via the VPN connection.. though in that example it just means Amazon can monitor your internet usage rather than your ISP.