This is so cool that I'm just sitting here giggling about it. Many newer computers, with newer BIOS, are able to boot from a flash memory card. My HP 2133 systems can do that. So I just used the ...
The addition of a built-in SD card reader to the 13" and 15" MacBook Pros may have dubious utility for many users, but Apple has seen fit to include at least one feature with lots of potential use.
Raspberry Pi and other SBCs can boot an operating system from SD cards and USB devices. I own multiple SD cards and am a fan of swapping them to instantly switch to a different OS, such as RetroPie, ...