Sway still primarily counts as a WM + Compositor, but considering it has keymaps, autostart, and libinput config mechanisms embedded in it, I would say it borders a desktop environment.

The inhibit_idle specifier is cool, thanks for the pointer. This two liner can be replaced with:

for_window [all] inhibit_idle fullscreen

I’d recommend tmux for that particular use. Screen has a lot of extras that are interesting but don’t really follow the GNU mentality of “do one thing and do it well.”