[caw]

I've got a 2025 Ioniq 5 SEL (US-made, US-spec), and I have both phone-as-key (on an Android phone) and a key card. As @Coastal suggests, the trick is to use the car's UI, not your phone's, to register the key card. I don't recall the precise procedure, but you need to find the option in the infotainment screen to manage keys, select the option to register a key, and place the key on the NFC reader (which doubles as the wireless phone charger) for a few seconds when prompted. Also, be sure you have the correct key card; Hyundai sells several, and the one for earlier model years of the Ioniq 5 does not work with the 2025. The correct part number is S8H81-AD000. At the time I bought mine (a couple of months ago), none of the local dealers knew what the right part number was, and most of the online Hyundai parts sellers did not list the 2025 Ioniq 5 as compatible with that part number.

Be aware that, in the event of a failure of the 12v battery, relying exclusively on the phone-as-key and key card will be inadequate, since those tools both rely on battery power. Teslas have an externally-accessible connector you can use to apply power (IIRC, the manual says a 9v battery should do the trick), but AFAIK there's nothing like that for the Hyundai Ioniq 5. Thus, to be safe you should carry the mechanical key that dangles off the bulky key fob that Hyundai provides. Fortunately, it's small enough that it's not too much of a hassle. I keep mine in my wallet, where it folds; it fits fine there.

Thanks for the pointer. So in the case of a battery drain/failure, the order of operations would be 1. Use the mechanical key to unlock the door, 2. Open the hood, 3. Get a jump to add some charge to the battery, then 4. Start the car using the key card?