To provide access to objects in Cloud Storage, you must either configure signed URLs or give the bucket and all of its objects public access for allUsers.
If you decide to provide allUsers access, you can verify object-level access as follows:
In the GCP Console, open the Cloud Storage browser.
Click the bucket to view the Bucket details page.
In the Public access column, hover over the exclamation-point icon and click Edit access.
For each object in the bucket, ensure that the following permission is set:
To learn more about access control and IAM for Cloud Storage, refer to Cloud Identity and Access Management.
To learn more about signed URLs, refer to Using Signed URLs.