[dmos62]

I tried to google around, but info was very thin. The bbzero github repo was last updated 4-5 years ago. Is this something that's bolted on top of the current WM, or is it a veritable replacement, in that the vanilla WM is unloaded and doesn't use resources?

The concensus, whether correct or not, is that Windows WM is tightly coupled with the rest of the system.

[deaddodo]

That's how it's always been. Litestep/bbZero/etc have always just replaced explorer.exe, but ultimately the Windows system is much more coupled than the Linux one. So you're still going to be using functionality beyond the "window manager".