There was a time when programs and applications were installed on computers using floppy disks. A kinder, gentler time. A glorious time. But, it took forever to install programs such as AutoCAD from a seemingly endless tray of 1.44 Mb floppies, which was later phased out in favor of CD ROMs. Some enthusiasts still take advantage of 3.5" drives using old 486 PCs as with any retro piece of technology. Most of today's operating systems couldn't fit on those disks, much less their kernels.
That used to be the notion, as Krzysztof Krystian Jankowski managed to create a Linux OS that boots from a single floppy, with 400 Kb of free space for adding additional scripts and programs. Known as Floppinux, the disk doesn't rely on old, outdated Linux versions but rather the 5.13.0-rc2 Linux kernel, along with BusyBox 1.33.1 utilities. Of course, Jankowski had to trim some fat off of the OS to get it to fit on the floppy, which is targeted to run on an i486DX-based system, and only the terminal is used as there is no graphics support.
Floppinux does have support for RAM, TTY, PRINTK, ELF, other applications, and Kiosk mode. Jankowski has uploaded a detailed walkthrough of his Floppinux build on his project page.