Notifications or notices are one underestimated feature of HA. 
@ccpk1 did something similar, I use it as the basis for the system I implemented for myself.
Take a look here, maybe you can find some inspiration for your own implementation.
One thing I’d note though: I wouldn’t work with conditional cards in the frontend, rather with auto-entities. That moves the “logic” into the backend, and you can use this logic in all places you want. Eg. in your case, you have the conditional logic in a frontend card. If you want that code shown in another place, you have to duplicate the logic.