If you don't have your phone for any reason, there is a sequence of buttons that you press that also disarms the device. Having your phone with the app active or the fob with you allows you avoid having to disarm the device via the button sequence. If you lose your phone, it is pretty simple to download and activate the app on your new phone.
When you get the device installed, the installer will program a default button sequence. My installer (incase yours does something different), then showed me how to change the button sequence. Since I was the very first 2023 that had ever had this installed by any IGLA installer, they were not sure which buttons I could use to program, but also showed me how to test buttons to figure out what worked or didn't work if I got curious. In 2022 and prior model years, buttons on the steering wheel, driver door and dash worked (some, not all). They'll also show you the button sequence that puts the truck into service mode and how to take it out of service mode.
Have a case of amnesia and forget all of this? They also give you a card that serves as an emergency back-up that gives you a special sequence unique to your device to get in to reset codes, etc... This is very important to safeguard.
One other note, my installer set mine up so that disarming the device is necessary to shift out of park. If someone were to remove the device, they would still not be able to shift it out of park. You can have it installed in a way that would allow a shift out of park with the device removed. I preferred my approach as it then doesn't matter if a thief has the time to locate and remove it, although there really is no way for them to know it is installed as it does not transmit any signals, and unlike the Ravelco, there is no visible indicator that something has been installed.