Probably one that can live boot and run right off of USB. There's a computer, you might be able to use it without knowing how to log on by booting from that stick. Now you might send/receive messages in a dire circumstance.
Also, having a live USB is really handy for doing PC maintenance when the installed OS gets borked somehow.
Check out Ventoy, it's a utility that lets you boot up any disk image from usb storage. For me, it condensed a keyring full of single-purpose flash drives down to just one.
There's probably an updated version available somewhere. Slap a drive in and load any ISO, and it can mount it as a virtual disc drive, or you can switch it to be detected as a regular external drive if you prefer, or both at the same time. I use it for booting my copy of Hiren's Boot CD I've been lugging around for eighteen years, live-boot Linux and Windows PE/recovery environments, it's brilliant.