One of my first jobs, back in the 1980s, was a project for a government department that the supplier (Wang Computers) had bet on MS-DOS being multi-process.

Of course, it wasn't but there was MP/M-86/CCP/M/CDOS/DR-DOS which allowed you to have 4 "users"/virtual TTYs.

So we ended up using that along with some tweaks to the software (including an IBM 3270 emulator, MS-Word/Excel (the DOS versions), and a custom software app) that ended up getting deployed to a few hundred government offices.

Mostly worked except some of the software really didn't like the fact that it was being swapped out of keyboard/screen access.