I’m aware of lovelace_gen, but I haven’t needed to use it. My dashboards are almost completely made up with the custom button card, which has its own templating mechanism. I think it’s best to use the custom button card’s built-in templating mechanism because it’s tuned to what the custom button card is capable of.
I do, however, have my dashboard sections organized as separate yaml files so that I can re-use them on different dashboards. That technique has worked well for my wall tablets, where I have a dedicated dashboard and user for each tablet so that each tablet is appropriate for its location. The re-usable sections don’t require adjustable configuration based on where they are displayed, so the split yaml approach is working well for me.
I have been keeping lovelace_gen in the back of my mind for when I need more templating.
If you haven’t found them, here are some other posts on my UI elements:
