I think I need some help. Pulumi says we can use a service principal to deploy our stack however the Azure CLI keeps saying that the service principals arent supported. What should I do instead? My stack is deployed from a container built by GHA

You can use a service principal, but to do that, you need to pass environment variables to the pulumi CLI. Azure CLI itself doesn't support that. However, if you're doing GHA, I'd recommend using OIDC instead, it's really easy to setup, and means you don't need to use static credentials (it uses a service principal under the hood).

Yeah I’ve been trying to get the company to allow that