Trigger-based template sensor: using "this" inside "trigger" not possible I guess

Configuration
1

Consider this trigger-based template sensor:

template:
  - trigger:
      - platform: template
        value_template: >-
          ...
    sensor:
      name: xyz
      state: >-
        ...

I may use a “this” variable inside the “sensor” section.
But can I use this variable inside “value_template”?

Use-case:
some “sensor.xyz” depends on “sensor.xyz_xyz”:

  - trigger:
      - platform: template
        value_template: >-
          {% set ENTITY_ID = 'sensor.xyz_xyz' %}
          {{ ... do smth with ENTITY_ID ... }}

But I would like to declare as:

  - trigger:
      - platform: template
        value_template: >-
          {% set ENTITY_ID = this.entity_id + `_xyz' %}
          {{ ... do smth with ENTITY_ID ... }}

Have not tested yet by myself, but I doubt that “this” may work here…
Also, ONE trigger may be used by several sensors which is one more prove that “this” cannot be used here.

2

this is only available in the sensors themselves. the trigger occurs before the sensor(s). Just take a step back and think about this logically…

what would this be in the trigger if yoru configuration was

template:
- trigger:
  - platform: ...
    ...
  sensor:
  - name: x
    ...
  - name: y
    ...

This is valid yaml. So if this was allowed in triggers, what would this reference? x or y? Typically, you can use these types of scenarios to answers these questions.

3

A similar thought came to my mind earlier:

Thanks a lot for your prove!