How might one accomplish the following using the "native" GCP Pulumi library? https://www.pulumi.com/registry/packages/gcp/api-docs/storage/getprojectserviceaccount/

There is not currently an equivalent API in Google Native. This is tracked in https://github.com/pulumi/pulumi-google-native/issues/119. You can easily mix and match Google Classic and Google Native - so you can use the former API along with resource in Google Native for now.