OP said less than 40MB. You can build Slint binaries targeting embedded devices. So a few hundred KB for a small application. Still arguably too much space but gui frameworks like slint use a domain specific language that generates more verbose code than what a human would typically write. Probably in the interests of being generic.

Man, as a C# dev, I'd kill for a single exe output. The binary being only 40MB is an absolute fantasy.

We have a project at work, it's nothing crazy, mostly shuffling data from one pipe to another, maybe a few thousand lines of code. A true standalone build including dotnet is over 180MB. The build that relies on the system dotnet install is still over 50MB. It's not even a GUI, it's a background service.

Things on Windows have a bad habit of enormous binary bloat, I'm not sure why. I don't think the problem is near as bad on Linux in general, but I don't have enough experience with linux dev to really say

I don't know for certain but expect it comes from comparing solutions with those based on virtual machines like Java's. The requirements in the original article look like a corporate wish list.