Yep, I once made a good living getting drivers into high memory and making those menus in config.sys. Installing network drivers and Netware client. People were quite happy to see me when I arrived.
For some reason I thought DOS had already been opened.
They have open sourced a few versions of DOS, including 4.0 I believe. This is just the latest.
For me, DOS 5.0 was the best. Would love to see that.
And of course we have both FreeDOS and SvarDOS now.