city, can be used as {{city}} in your message.The app must be running at the scheduled time. If it was closed, overdue jobs start as soon as you open it.
Easiest: install the free ntfy app from Google Play, tap +, and subscribe to the same name you type above. Use a long random name, because anyone who knows it can read your alerts. Telegram below is optional.
Telegram gives an instant phone notification with sound, even when this app is closed. In Telegram: open @BotFather, send /newbot, copy the token. Then open your new bot and press Start. Message @userinfobot to get your chat ID. Save, then press Send test alert.
Webhook callback URL for Meta: (needs a public https address, see README). Subscribe to the messages field.
Exports contacts, messages, schedules and settings in one file. Import it on the new device.
Only people you add here can log in. You (admin) always have full access. A person can use only what you tick.
Tell the person their username and password yourself. Changing a password or disabling an account logs that person out immediately.