I developed a small Google Cloud plugin based on the official cloud-sdk docker image.
The main rationale was to be able to deploy GCloud Run services, while trying to secure the way the credentials was handled.
It supports definition of config variables, export of results of commands into environment variables so it can be reused in subsequent commands, command flags, and optional ability not to stop the pipeline if one command fails.
The plugin is written in Node as it became a bit cumbersome to write it in bash, and as I know too little of Go.
I suppose there is more to be done, so any contribution is welcome!