I haven't really used Windows much for years, but doesn't it start shutting down once evaluation period is up? 'Windows will shutdown in 30 minutes unless licence key is added' etc., and the desktop background goes blue with some text about being unlicensed?
Also don't use the evaluation images.
I have not experienced that, which is why I questioned the difficulty. I've installed Windows 10 on a good amount of machines at this point, bypassing the NRO during the install process, and have not had any issues that prevented me from installing software/games or just using it like a normal PC, even after connecting it to the Internet.
However, my experience may be dated. It's been awhile since I've had to freshly install Windows. Perhaps things have changed.
Yes, I believe LTSC does have a harsher shutdown setting if you're out of the 90 day "evaluation" window. Standard Windows keeps working just disabling the wallpaper and showing a watermark which you might be able to ignore.
Consumer versions of Windows just put a watermark on your screen and disable changing your wallpaper and the like. You can use it indefinitely beyond that. And if you want the watermark gone, then Massgrave is your friend.