How to show the result of a Pyscript function in a mushroom template card

Configuration
1

I have a Pyscript function (exposed as a service) , that calculates a value, which I want do display as part of a string in a template card.

type: custom:mushroom-template-card
primary: This is the Titel
secondary: Info with value from RESULT FROM CALL-SERVICE
icon: mdi:flag
tap_action:
  action: none
icon_color: |-
  {% if is_state("sensor.ttt767", "on") -%}
    amber
  {%- endif %}
hold_action:
  action: none
double_tap_action:
  action: none