[IiydAbITMvJkqKf]

The situation on x11 isn't too different - there's basically only metacity, kwin, and openbox in the stacking WM world, plus a thousand tiling WMs.

In wayland there's additionally KWinFT, hikari, and wayfire. Although neither of them are comparable to the classic Windows/Mac WMs.

[mrweasel]

There are a ton of small stacking X11 window manager, sure many of them are old, but they're still maintained.

[ijlx]

The arch linux wiki has a good list: https://wiki.archlinux.org/title/Window_manager#Stacking_win.... Haven't looked into how many of them are maintained.