> what cross-platform libraries are available for Nim!
Things might have changed over the past couple years, but, at least at the time, there weren't any (usable) Nim bindings for either.
There is no (grammatical) article in its title. You seem to be assuming the article is implicitly "the", which would imply that it's intended for a more-or-less universal audience. It could just as easily be "a", which would then mean that it's more of a personal rant about the author's specific situation. I'd argue that the leading two sentences in the italicized portion of the article imply that it's the latter.
For the sake of throwing my own $0.02 in, I also have a historical habit of blithely ignoring wxWidgets and QT for my hobby projects. Their being written in C++ bit is a bit of a deal-breaker for me. The quagmire of interacting with C++ code from a language that isn't itself C++ in a cross-platform way results in me shaving my fill of yaks during working hours; I have little taste for doing even more of it during time that's supposed to be reserved for fun.