Buy you a backpack-fridge
The best recommendation to go to La Graciosa is buy a backpack fridge in Decathlon. Put every night in the freezer one or two large water bottles, and so will make the “ice” during the day. Forget the typical blue plastic plates. It’s too heavy, only last a couple of hours and then you can not get the drink as if about water bottles.
Do not let either of bringing you a couple of tupperware to take you salad, fruit or whatever you want to the beach. Here, thankfully, the beach bars or beach kiosk is science fiction, so all drinks and food has to come from home!