I'd recommend using Pushover (app in your mobile store, iOS or Android).
Its a one time purchase for the app, after a 7-day free trial, it costs $4.99 USD once, per-platform (iOS, Android, Desktop), and you can use this along with most automations.
It works quite brilliantly.
The Pushover driver is inbuilt into HE now, but some help and guidance here.
