A DE tries to be a full operating environment, it has panels and configuration tools and (...) all as part of the package
A WM only does window management, and other things need to be added separately. The line blurs a bit since most people who use WMs end up adding a lot of other stuff to them to the point it might as well be a DE, only it was built piecemeal.
None that I know of. Though you can build your own operating environment centered around Hyprland. Their wiki is pretty good and their config files are nice and simple to understand. I did that for a lark a few months back.
.... The catch is that, y'know, it's a whole afternoon spent tinkering to get it right.