Hi everyone, our team was not able to leverage JSON keys as a method of authenticating to GCP so we had to go a different route. We ended up going with Application Default Credentials authentication method (How Application Default Credentials works | Authentication | Google Cloud) in which a service account is tied to a machine/server. After this was set up, we installed the Google.Cloud.BigQuery.V2 dependency. With this set up, we were able to replicate the steps in .NET client library | Google Cloud by using Assign activities
I hope this is helpful!