I saw in the documentation that HA only does email messaging and I understand why the carriers had to drop their SMS-TXT gateways protect us all from even more text spam.
Still, RCS texts through an inexpensive cloud add-in would be of interest to me for notifications of power failures, leaks, etc. Come on Nebucasa cloud - add this feature!
So today you could realistically do:
Home Assistant → BlueBubbles → iMessage
Home Assistant → Quo API → SMS
Home Assistant → self-hosted ntfy → push notification
Home Assistant → self-hosted Signal REST API → Signal
You live in a age where you can literally make a cheap little integration with no knowledge lol but there are some existing solutions already
Also
Home Assistant → Llamalab app on Android phone → SMS
Or simply
Home Assistant → Companion App notifications