It is possible to run Windows containers, but only as a container in a Compute Engine VM instance. I would refer you to this article in the GCP blog. Please be aware that there a few known issues that you should read before deploying Windows containers in Windows VM instances.

For GKE, there is currently a Feature Request. Other customers have asked to include future support for Windows containers in GKE. This is a request through official means. Google will consider the need based on its feasibility, or the number of customers who ask for it, but they can't guarantee an implementation or provide you with an ETA for it.