I'll add comments to this thread with Github projects that I can find by searching for "postgres listen/notify" on Github.

https://github.com/graphile/worker

    // Line 535 in src/main.ts
    client.query('LISTEN "jobs:insert"; LISTEN "worker:migrate";')

Every worker pool seems to listen on the same shared channels: jobs:insert - all workers get notified when new jobs are added worker:migrate - all workers get notified about database migrations