• jwm an window manager

• dmenu_run as launcher; alternatives: rofi or xlunch (https://github.com/Tomas-M/xlunch)

• xmenu for an easier popup than jwm

More of that I understand that commercial LLMs are trained mostly, always exclusively on open source code. So, to my mind it must be (as it will be fair) free to all open source projects, but the world is not perfect.

Yes. I have mentioned that Cinnamon X11 handles HIDPI well. KDE X11 does so as well. I then explained why I chose KDE over Cinnamon:
1. Lower CPU usage.
2. Support for both X11 and Wayland, where Wayland provides better automatic configuration (resolution, brightness, and refresh rate) on multi-display setups.

I have a HiDPI display and an external monitor; the settings for the internal and external displays must be distinct. 
Cinnamon handles HiDPI reasonably well but its multi‑display configuration is less effective than Wayland. 
All other X11 desktop environments (except Cinnamon) look terrible. 

Also KDE uses fewer resources than Cinnamon when Baloo is disabled and unnecessary components are not installed. 
In terms of lighter usage, I am concerned about CPU usage rather than the 100–200MB difference in RAM.

I run Devuan XFCE on my 2GB/16GB eMMC chromebook quite happily.

But if you want something lighter, maybe take a look at JWM, (I now use that as a secondary desktop system).

I'd suggest installing from a Devuan ISO. I'd also suggest trying many DEs until, over time, you feel drawn to one DE for whatever reason/s. It's a personal choice.

TBH, I have Gnome on a tablet as it's well suited for touch screens and that tablet is only used by family members for web browsing and watching videos, but I would never install it on a desktop or laptop PC.

I can't see how anyone would find that usable or useful. I can't envisage who it's designed for or what use case.

I dislike automobile analogies, but it's akin to designing a car without an engine, or controls - as that's far safer and reduces obviously support overhead.

"The idiots can only do what we allow them"

Thus, your theoretical tech support only have to deal with problems 1 to 10.

The usual answers to 1 to 10 will be "reinstall".

"I stopped chasing perfection in favor of consistency."

Same here.  I landed on Mate after stability issues with Cinnamon ages ago and have used it as my daily driver for years.  I'm also a fan of XFCE.  If I could get Mate to stop rearranging the icons in the desktop panel periodically between logins, it would be about perfect.  Not much pizzazz, but everything I need to get work done with months (year?) between reboots.

Cheers,
--K

My workflow requires a robust "Round-robin" multitasking environment.
For a simple example: I maintain 31 different browser instances (with more than 10 windows and 1,000 tabs per instance). Each browser instance is topic specific (Publishing, DevOps, Typography, Programming, Home Maintenance, Adhoc Research, et cetera).  And I maintain many specific-use Virtual Machines.

I don't use AI, BTW.  I myself do the all the thinking, exploring, trying, evaluating, learning, adapting, growing, appreciating, and enjoying.
I have developed enterprise projects that lasted more than 14 years (as the preferred solution), across 15 different industries.  My longest project is still very active, from 2003.
(My journey into coding began with APL in 1980, over a 150 baud modem - via a rotary 'all-in-one' acoustic coupler.  I've seen and experienced a lot.)

For me, KDE on X11 is transparent to the way I think, work, and pivot.  When Devuan 8 eventually comes around, I'll examine SonicDE on X11 for workstation use.

Yes, KDE is memory heavy, and yes, X11 has been declared 'obsolete'.  But for my own soul, nothing else provides me the flexibility I need - season by season.