The following example first processes a bucket. If uniform access is not enabled then the object is processed. If public access enabled on the bucket or the object, the object is Public. Refer to https://stackoverflow.com/questions/68722565/how-to-check-if-a-file-in-gcp-storage-is-public-or-not

is_object_public.py

import	sys
from google.cloud import storage

# Replace with valid bucket and object names
bucket_name = 'example_bucket_name'
object_name = 'example_object_name'

# Instantiates a client
storage_client = storage.Client()

# Process bucket level access
def process_bucket(bucketName):
	bucket = storage_client.get_bucket(bucketName)

	configuration = bucket.iam_configuration
	uniformEnabled = configuration['uniformBucketLevelAccess']['enabled']

	public = False

	policy = bucket.get_iam_policy()

	for binding in policy.bindings:
		for m in binding['members']:
			if m == 'allUsers':
				public = True

	print('Bucket:', bucketName)
	print('  Uniform Access:', uniformEnabled)
	print('  Public:', public)

	return uniformEnabled

# Process blob level access
def process_object(bucketName, objectName):
	bucket = storage_client.get_bucket(bucketName)

	blob = bucket.blob(objectName)

	policy = blob.get_iam_policy()

	public = False

	for binding in policy.bindings:
		for m in binding['members']:
			if m == 'allUsers':
				public = True

	print('Object: gs://{0}/{1}'.format(bucketName, objectName))
	print('  Public:', public)

if __name__ == '__main__':
	try:
		uniform_enabled = process_bucket(bucket_name)
		if uniform_enabled is False:
			process_object(bucket_name, object_name)
	except Exception as ex:
		print("Exception: {}".format(ex), file=sys.stderr)
		sys.exit(1)