Hi @juicydisorder,
Welcome to Google Cloud Community!
To access the Google Business Profile API (GBP API) using a service account, you need to grant the service account the appropriate IAM roles:
Ask your administrator to grant you the roles/iam.serviceAccountCreator IAM role on the project.
Grant the service account the roles/resourcemanager.projectIamAdmin role to give it access to your project.
Confirm Google Business Profile is turned on
If you’re using a Google workspace account, make sure Google Business Profile is turned on for your account. If it’s not, you’ll get an error 403 - PERMISSION DENIED when using the GBP APIs.
You can also create custom roles if there isn’t a predefined role for the access level you want.
Other steps to access the GBP API include: Getting a Google Account, Trying out Business Profile, Creating a project in the Google API Console, and Requesting access to the API.
You can review the deprecation schedule and instructions to migrate from the v4 reportInsights API method to the Google Business Profile Performance API.
I hope the above information is helpful.