I just found a comment from @tom_l here Allow scene.create to use device_id instead of entity_id - Feature Requests - Home Assistant Community (home-assistant.io) which seems to indicate that I cannot use a template with a device_id.
In the GUI, it supports the following action types: Condition, Delay, Fire Event, Activate Scene, Call Service, Wait, Wait for Trigger, Repeat, Choose, and Device. It does not seem to include Entity.
The other question though would be though, would I be able to send a notification to mobile phone entity as the only entities I see are device_trackers and sensors?
The blueprint provided by @vorion does use the following code for mobile notification (shortened to relevant code) Send camera snapshot notification on motion - Blueprints Exchange - Home Assistant Community (home-assistant.io)
blueprint:
name: Send a camera snapshot when motion is detected
domain: automation
input:
notify_device:
name: Device to notify
description: Device needs to run the official Home Assistant app to receive notifications
selector:
device:
integration: mobile_app
action:
- device_id: !input notify_device
domain: mobile_app
type: notify
The code in automations.yaml looks like:
use_blueprint:
path: vorion/send-camera-snapshot-notification-on-motion.yaml
input:
notify_device: 40e14b2f45f098cb1524fecd45624bb1
The code is able to refer to the device_id, however, I try to pass the device_id to a script.
- device_id: !input notify_device