Unfortunately, if you are insisting on a single exe file, then you have to be way more flexible on your requirements than the author is. There’s a reason that practically every Windows program has an installer. It’s stupid and a waste of time but also probably more of a waste of time to try to be the exception to this rule.

Frankly I don’t see why C# targeting an old (3.5?) .NET framework version wouldn’t work for the author. There seems to be a tendency to fixate on how things should be vs where we are now. C++ native GUI dev is not a mainstay like it used to be.