If you want to forward *all* internet traffic through the VPN, and not just use it as a server-to-server subnet, you can add `0.0.0.0/0, ::/0` to the `AllowedIPs` definition of the peer you want to pipe your traffic through.
Make sure to also specify an IPv6 catchall even when only forwarding IPv4 traffic in order to avoid leaking IPv6 packets outside the VPN, see: