Trying to setup a VPN to access Google Cloud Storage bucket

Hello!
I’m tring to implement a solution with a site-to-site VPN from my on-premises server to my google cloud storage bucket.
The idea is to make my Backup Server (Veeam) to send backups to the bucket through a VPN Tunnel (classic tunnel with IPSec standard), instead of going through internet.

Veeam shows this KB when configuring everything in GCP and onprem: https://www.veeam.com/kb4324

But I’m not understanding how to transfer between GCP VPCs and Cloud Storage.
For example, in Amazon you can use AWS PrivateLink or interface endpoint. This enables you to access Amazon S3 buckets in AWS over a private connection without exposing your data to the internet.
As for that you have to create and endpoint and associate it to the VPC subnet where you got the VPN tunnel created.

In the case of GCP, endpoints or ENIs for Google Cloud Storage bucket does not exist. How can I make it work in that way?

DNS, configure on prem DNS for private.googleapis.com, then make sure those IPS are routed via the IPsec VPN.

The doc describes it. But you need to make those changes in your on prem DNS server.