There is an operating system that's like MS-DOS called "FreeDOS" AKA "PD-DOS". It's a disk operating system for IBM PC compatible computers. It provides a DOS environment for running legacy software and supporting embedded systems. This disk operating system can be booted from floppy disk or USB flash drive, and is designed to run well under virtualization and x86 emulation. FreeDOS is composed of free and open-source software, unlike MS-DOS.
They still have newer versions of FreeDOS, but there are older versions; it came out in 1998 by the way. You could at least do the alpha and beta releases of FreeDOS, which came out from 1994-2004.
So yeah, this is just an idea for a disk operating system that you maybe could offer.