Hey, I've been using Pulumi for a few months now, and I have this practice that I'm not sure if it's a good or a bad pratice. When getting values from the stack, I often find my self using pulumi args e.g. gcp.compute.BackendServiceArgs. To be more precise I would create an interface and assign a variable in that interface that is type of gcp.compute.BackendServiceArgs. Is this a good or a bad practice? Is there a better way of doing these things?

It is neither good nor bad: the interface is exported and public, so you're free to use it. Since you say getting values from the stack, you should note that the args interfaces describe inputs, and getting implies outputs. There may be cases where not all inputs are available as outputs, so you may get some unexpectedly undefined values. For example, the subnets values for awsx.ec2.Vpc is not available as an output (iirc?).