Unroll group to show only true entities in group

Configuration
1

Hey,

I use a (binary sensor) group with all my window sensors.
Then I use alert to trigger on opened windows.

What I now miss is the option to notify me with the opened windows, so a “list” of true entities in this group.
Is this possible with a template?

Thanks for your help

2 
"{{ expand('binary_sensor.windows') | selectattr('state','eq','on')|map(attribute='name') | list | join(', ')  }}"
3

Thanks a lot.