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, ...
There's no shortage of operating systems you can try on a Raspberry Pi. These include general-purpose distros like Ubuntu and Fedora that are ideal for desktop and server use, as well as more niche ...
A Raspberry Pi multiboot lets you pick Raspberry Pi OS, Ubuntu, or MX Linux at startup without changing SD cards.