We sold a lot of QEMM but not many copies of DESQview, but I lived in a small community then -- the Isle of Man.
I have blogged about it in the past ( https://liam-on-linux.livejournal.com/52294.html ) but Quarterdeck had a chance to redefine the DOS industry with DESQview/X, but it came out too late.
In the late 1980s there was an awareness that GUIs were the Next Big Thing and there were various GUIs on DOS: DR GEM, PC GEOS, and others. Quarterdeck went for it, making a brave but logical choice: don't invent your own -- adopt industry standards.
At the time, there was only one open industry standard: X.11 and the Motif window manager and widget set. So, Q'deck enhanced DESQview until it was able to run an X server and Motif. It added virtual memory support to DOS, supported a couple of vendors' DOS TCP-IP stacks, and produced a multitasking GUI layer for DOS, but instead of home-grown code, it used Unix tools where it could. For example, scalable fonts were provided by Adobe Type Manager, the leading scalable-font add-on for Classic MacOS.
It was pretty good. Like text-mode DESQview, you could run DOS apps in windows, but now it could just scale the text when the window got smaller. You got new graphical apps and a simple file manager and app launcher. You could port Unix apps. It was an X server, so you could run remote X apps with the display on the DOS machine.
It was also an X client, so remote Unix machines could connect and run native DOS apps on real DOS hardware at full speed.
It was very impressive, and up against OS/2 1.x it looked good.
But it took so long to ship that Windows 3.0 came out first, and then it was basically all over.