No server, no internet, no laptop. Two devices connect straight to each other over WiFi.
One person creates a room, the other joins using a one-time connection code.
Room host
Add each device one at a time. For every device, you'll get a code to send them, and a
spot to paste the code they send back. Send codes any way you like — WhatsApp, reading aloud, Nearby Share, etc.
— this app doesn't transmit them for you.