Other ways to write 'on' / 'off'

[tom_l]

No, Lovelace does not support templates.

You can use this custom card to add Javascript templates (not jinja).

100% Templatable Lovelace Configurations

Lovelace Templates I’ve gone and made a crazy card that allows you to pretty much template anything in Lovelace for your card configurations using any information available on the frontend; states, attributes, user, etc. Want state/attribute-based icons? DONE! Want dynamic stacks; vertical vs horizontal based on user? DONE! Want OR conditionals? DONE! The list is pretty much endless and I’m sure you all will come up with some crazy stuff. Be sure to share. Go nuts! Enjoy!

Also a word of warning about your use of quotes, you need to put double quotes outside your templates, otherwise this happens:

value_template: '{{ is_state('