What you want is possible, but requires work.
You’ll need to have the following code in all your templates:
Automations where you aren’t using trigger object (trigger.to_state… etc)
{% set option_number = state_attr('input_select.xxx','options').index(states('input_select.xxx')) %}
Automations where you are using the trigger object
{% set option_number = state_attr(trigger.entity_id,'options').index(states(trigger.entity_id)) %}
The output of these templates is an index position of your input_selection. Remember list indexes start at zero.
Example
These are the options in your input_select.xxx
- Item A
- Item B
- Item C
- Item D
If your input_select.xxx is set to Item A, your output_number from the template contain a value of 0 after executing the template line supplied above.
If your input_select.xxx is set to Item B, your output_number from the template contain a value of 1 after executing the template line supplied above.
If your input_select.xxx is set to Item C, your output_number from the template contain a value of 2 after executing the template line supplied above.
If your input_select.xxx is set to Item D, your output_number from the template contain a value of 3 after executing the template line supplied above.
So, pretty much your selection option order is what drives what number you get from that template line.