I use multiple DEs (including WMs and TTYs itself). So I don’t use (enable) GDM. But I noticed that literally all display features like logging, locking, screensaver and even screen blanking, integrated into GDM. This raises difficulty in using GNOME DE itself.
Is there any other way I can utilize gnome’s idle monitor and “dpms off” manually ?
Not really, considering GNOME is used with GDM pretty much all the time.
That being said, what speaks against using GDM in general, to start GNOME or other Desktops? GDM is not limited to only start GNOME.
Because automatic startup of gdm also invokes many gnome related processes in the background, like gdm-wayland-session, gnome-session-worker, gnome-shell, colord, gvfsd-fuse, gsd-power, gsd-print-notifications, gsd-{all-other-subprocesses}, pipewire audio services, mutter-x11-frames, xdg-desktop-portal-gtk, etc.
It’s a cascading background process bloatware initialization that I don’t need to begin my operating system with.
I access gnome desktop with gnome-session --wayland command (or I’d say a stable script that also sets env variables and commands related to it). Logging out this session also prevents persistance of the above unnecessary background processes too. This doesn’t happen with gdm enabled.
Without that “bloatware”, the functionality you’re looking for is not available. It seems you have a very skewed notion of what is “bloat”.
I do respect gnome. For me, bloatware is anything that is in the background process that is not contributing in my current workflow. Enabling gdm and using other DEs/WMs obviously marks gdm’s subprocesses as bloatware. Not sure why that makes me skewed. It’s textbook definition of bloat. It’s not a bad word. Just an unusual one.
GDM only starts shell, and for that matter it’s associated services, if you launch a GNOME session.
If you select a different session type, like WindowMaker, from the cog menu menu in the bottom corner, it’ll start that instead. Most WMs etc should turn up there automatically when installed, or you can easily drop in your own configs — it’s just a keyfile.
I’m sorry I don’t wanna use gdm.
As @ebassi said that it’s not possible to blank screen manually using gnome idle monitoring and gdm is the only option. Not at all UNIX friendly.
The concept of “Unix friendliness” is incompatible with the concept of “user friendliness”. Or, you know: the concept of actually mattering in 2025. Luckily for us, though, GNOME isn’t striving to being friendly to a OS from the ‘70s that was famous for having so many proprietary forks and variants that it necessitated every environment and application to target the minimum common denominator, instead of being useful.
“Unix friendly” and “user friendly” are not mutually exclusive. Both can be achieved. One is code base where the projects are divided based on that “one task doing very well”. Removal of that program should only affect that specific task & not others. Another is integrating all those projects seemlessly so that user doesn’t face any issues in terms of performance and experience.
This sort of task/feature clubbing is done to sell an ecosystem that can’t be escaped. (cough:cough:Apple)