On both mac ports, native resolution on eg. MacBook Pro is not supported.
For example on my 16", the max resolution offered in game is 1728x1080, which is half of the native 3456x2160 (screen area below notch / menu bar). Since it is half, I suspect the issue to be with not taking into account NSScreen's backingScaleFactor.

NSScreen *screen = [NSScreen mainScreen];
CGFloat scale = [screen backingScaleFactor]; // is 2.0 on retina screens
NSRect rect = [screen frame];

CGFloat widthInPixels = rect.size.width * scale;
CGFloat heightInPixels = rect.size.height * scale;