Anybody know how this compares to just running win 10 or 11 LTSC?

Last time I clean-installed Windows 10 32-bit, then manually uninstalled the things I didn't need (which is alot) and takes a little while, then converted to Compact Mode using Admin CMD, it came out less than 5GB on the C: volume.

That's Windows alone without installing anything else. Also with System Restore off, plus disk swap & hibernation disabled.

Nothing heroic like removing Edge, but Edge was definitely not updated nor was the OS online yet. I would expect bringing that image up to date now would more than double it.

Going further when you manually disable features and background services you know you don't need, it goes down below 1GB in memory too, and you can easily browse places like HN on a PC having only 2GB memory and no disk swap enabled.

Watch your step with such low memory though, you can't browse just anywhere and it gets a lot easier to step on all the proliferating newly placed "land-mines" if you're not careful :\

From the article:

"The resulting OS is not serviceable. This means you cannot add languages, drivers, or features, and you will not receive Windows Updates. It is intended only for testing, development, or embedded use in VMs where a minimal, static environment is required."

Depends what you mean by "just running". If I had to run a non-VM'd windows, I'd opt for a mostly-full version (10 IOT LTSC or 11 LTSC)