Authenticating a google.storage.Client without saving the service account JSON to disk

For authentication of a Google Cloud Platform storage client, I'd like to NOT write the service account JSON (credentials file that you create) to disk. I would like to keep them purely in memory after loading them from a Hashicorp Vault keystore that is shared by all cloud instances. Is there a way to pass the JSON credentials directly, rather than passing a pathlike/file object?

I understand how to do this using a pathlike/file object as follows, but this is what I want to avoid (due to security issues, I'd prefer to never write them to disk):

from google.cloud import storage

# set an environment variable that relies on a JSON file
export GOOGLE_APPLICATION_CREDENTIALS="/path/to/service_account.json"

# create the client (assumes the environment variable is set)
client = storage.Client()

# alternately, one can create the client without the environment 
# variable, but this still relies on a JSON file.
client = storage.Client.from_service_account_json("/path/to/service_account.json")

I have tried to get around this by referencing the JSON DATA (json_data) directly, but this throws the error: TypeError: expected str, bytes or os.PathLike object, not dict

json_data = {....[JSON]....}
client = storage.Client.from_service_account_json(json_data)

Also, dumping to JSON, but I get the error:

with io.open(json_credentials_path, "r", encoding="utf-8") as json_fi: OSError: [Errno 63] File name too long: '{"type": "service_account", "project_id",......

json_data = {....[JSON]....}
client = storage.Client.from_service_account_json(json.dumps(json_data))

Per the suggestion from @johnhanley, I have also tried:

from google.cloud import storage
from google.oauth2 import service_account

json_data = {...data loaded from keystore...}
type(json_data)
   dict

credentials = service_account.Credentials.from_service_account_info(json_data)
type(credentials)
   google.oauth2.service_account.Credentials

client = storage.Client(credentials=credentials)

This resulted in the DefaultCredentialsError:

raise exceptions.DefaultCredentialsError(_HELP_MESSAGE) google.auth.exceptions.DefaultCredentialsError: Could not automatically determine credentials. Please set GOOGLE_APPLICATION_CREDENTIALS or explicitly create credentials and re-run the application. For more information, please see https://developers.google.com/accounts/docs/application-default-credentials.

If you have ideas on how to solve this, I'd love to hear it!