https://www.cnet.com/roadshow/news/2020-hyundai-sonata-digital-key-new-york-auto-show/

An NFC card, similar to what you'd open a hotel room with, is supplied as well. You can keep this as a backup, or give it to someone like a valet driver or parking attendant, so you can still use Digital Key even if someone else might need to drive your vehicle while on the go. 

Here's the caveat: Right now, this technology works with Android phones exclusively, since they're the only ones with NFC capability. Digital Key is standard on all but the base model of the 2020 Hyundai Sonata, which we expect to see in dealerships this October.