At some point I moved to a Mac because I realized that perfecting my window manager setup was just killing my productivity. I hope that one day I'll be able to get back to it – maybe when I retire.
Which is funny because macOS out of the box has some of the worst window management ever seen on any OS.
The thing I actually care about is navigating between windows by typing something that gets autocompleted. Spotlight or Alfred get me mostly there. In chrome I use Powerswitch to navigate between windows, and there's Cmd K for Slack. Having one interface for those would be grand, but I'm not holding my breath.
You're not holding it wrong, it's just a very primitive desktop environment. No snapping, poor external monitor support, defaults to magically moving desktops in relation to each other, etc.
If you want good window management right out the box, you won't get it from MacOS.
I'm still looking for an sxiv replacement, though.
By default, StumpWM lists normal buffers on C-x b, and X-windows using some other keybinding like C-t b