Nearline Storage

Does anyone know if we can configure Moonwalk to use the cheaper Nearline storage?

Yes.
Once your Nearline Storage Bucket is created in your Google account, you can set it to be a Moonwalk destination by using the Moonwalk Google Config tool.

However don’t just go for the cheapest without thinking about the ramifications. Information about availability SLAs and costs can be found here Storage classes  |  Google Cloud