This has the advantage of executing all your shell mcguffins too, so PYTHON4_LC_COLOR=Europe/Orange is set for the entire desktop session, not just the shells you launch from your desktop environment.
(By the way, exec is a fundamental Unix syscall of interest in that it replaces the current process’s code with new code. Your logout call will never run. The exec is the last thing zsh does before being replaced by sway.)
Due to the WTFPL having no restrictions it seems like it would be functionally identical to MIT-0 or BSD-0, as it wouldn't require attribution or a copy of the copyright/permission notice. It's about as close as one can get to public domain without being public domain.
In the Linux desktop world, "display manager" has various responsibilities but most people not steeped in system components might call it a "login screen". So this is a terminal-based replacement for GDM, SDDM, etc.
Most of that (e.g., keyring) is PAM, not the manager itself.
The xinitrc thing is for all intents and purposes just a command run before your session binary, and sometimes a few extra env vars. Arguably a bad design (just let that be up to the session binary), it oh well. History is what it is.
Appears to be a replacement for gdm that is console based (picking and launching your graphical desktop environment). A neat idea, I don't think this has been done before.
