Doesn't Hasura or Postgraphile do this better? They give a GraphQL API over Postgres with support for subscriptions, along with authentication, authorization etc.
Change data capture allows you to stream database changes to a message bus or stream which has much better support for backend service requirements. Example: if a downstream service goes down, how would it retrieve the missed events from Hasura? Using Kafka or a buffered message bus, you'd be able to replay events to the service.
Nevermind having to support websockets in all your services :/