itopia gives you an option of creating an instance with Linux operating system. You can select from Debian and Ubuntu versions.
Once the Linux machine is created you will need to log into the Google console and use SSH protocol to log into the Linux server from the Instances page.
In order to allow external access to the server please see the following article by Google: https://cloud.google.com/compute/docs/instances/connecting-to-instance#thirdpartytools
If you get access denied, you may also need to run sudo or sudo su before the command, the account Google creates for you should have sudo permissions.