Filtering of single entities

[Roemer]

It would be great to be able to allow filtering for single entities.
In my case, I have the following:

• light.livingroom controls if there is any current for the living room light
• light.hue_livingroom controls the hue light of the living room (which of course only works if light.livingroom is on

Now I want to hide the light.hue_liginvroom if light.livingroom is turned off and show it otherwise.
For that, I need to be able to add a filter just to the entity light.hue_livingroom.

Can that be added? It seems like someone already hacked this together (see https://community.home-assistant.io/t/is-there-an-easy-way-to-hide-entity-on-a-lovelace-card-based-on-state-of-another-entity/105065/7 and https://gist.github.com/randellhodges/7654a267a282b6c4a48b590748d13b9f)?