IBM used a DOS-based OS called "4690" for their point-of-sale systems, which IIRC had 32-bit extensions and various forms of networking including a weird 56kbps "token ring" type system that tills could (s-l-o-o-o-w-l-y) netboot off.

It's still in use, and although it's been replaced by Linux in current products there were bugfix releases at least as recently as late 2020.