When I got my Prius in January of 2004 pretty much nobody understood these cars. There were stories of valets getting out of the car without turning it off (engine stops, they think the car is off) and it rolls into a barricade. I never let anybody drive that car except the service guy at the dealership who drives it in and out at oil changes. I'd just tell people "This car is different."
Same with the Roadster. I didn't let anybody but the Tesla Ranger drive it when he came for the annual service and needed to do a check drive afterwards. Except one friend who I knew to be a very safe and careful driver, and I was in the car with him.
And same with the Model 3, except that I had to let Matson drive it on and off the shipping rack when I shipped it here. All went well except that they put a couple of stickers on it that I could not remove, but when I had the car detailed the detailer got it all cleaned off. I just don't go places that have valet-only parking. For Matson I bought a plastic card holder with a key ring on it so they could hang it on a key hook.
If I inadvertently found myself somewhere with valet parking, I'd just tell them that my phone is my key and I cannot leave my phone with them, as someone else suggested upthread. If they know about the key cards, I'd lie and say I don't have it with me.