The self-hosted roster hub already let staff see their shifts, trade, claim open shifts, ask for time off and report a call-out. The gap was that you had to open the admin page to find out. It can now post to a webhook you own.
Set NOTIFY_WEBHOOK_URL and your manager channel gets a line for each staff request. Set TEAM_WEBHOOK_URL and the team channel gets everyone's shifts when you publish. Slack, Discord, ntfy and plain JSON are supported through NOTIFY_FORMAT. It is off unless you set a URL.
Paid schedulers charge per user for push notifications. Here the message goes from your server to your channel, and nothing passes through a service we run. A message holds no wages and no admin key, staff-typed text is escaped so it cannot ping @channel, and a dead webhook never blocks a request.
It is tested against an injected fetch, not a live Slack, Discord or ntfy. Setup is in the README.