Note: The new default when creating a topic, also creates a subscription for the topic. New options can be explored by clicking the round info icon.
You can publish a message by going into the Topic, scroll to the bottom and click the MESSAGES tab. Click PUBLISH MESSAGE, then PUBLISH.
Under that, select a Cloud Pub/Sub Subscription to pull messages from. Choose our topic, and click PULL.
The message pull status shows different, but can be filtered in different ways under Filter Table.