Since Waitwhile is a web-based app, it works on practically any device.
Basically, any smartphone, tablet or computer with the ability to open a web browser and access the internet will work.
Standard practice for most businesses use at least 2 devices (e.g. iPads) for Waitwhile:
Kiosk tablet to Register Guests - see guide how to set up your kiosk
Staff-facing device to manage the waitlist/bookings among your staff.