Problem:
When I create a new VM on GCP, only networks that are available to me are the ones from my project only. I do not see shared subnets from other projects. Is it even possible to use shared ones with this plugin ?
Expected outcome:
I should be able to see and use shared VPCs.
Foreman and Proxy versions:
1.22.0~rc2-1
Recently added changes in Google compute resource fixes existing provisioning flow which was broken due to changes in Google APIs.
Unfortunately, with latest changes as well Foreman allows user to select only network from current project not subnet. I can see that there is already opened feature request for the same.
I am looking into this. You can also track progress on it using this issue link. If I am not missing anything then using subnet select option, user can use shared VPCs.
Thank you for this update. However, it seems like this is pretty old issue. I am not sure if it going to be done soon 
It is 11 months old and for Foreman 1.14. Was this even working before the latest API?
Did you mean shared VPCs support? then no, this wasn’t supported before.
Google compute resource itself was broken since long time due to changes in Google APIs as well as some library changes which is fixed now in latest release.
You can track progress on shared VPCs support using attached issue.