I think adding the following to CPUInformation::initialise() should mark hasNeon for macOS (DTK) and iOS. I have not tested it on hardware though, so it would be useful if anyone could?
#ifdef JUCE_ARM
{
unsigned int neon = 0;
size_t len = sizeof (neon);
if (sysctlbyname ("hw.optional.neon", &neon, &len, nullptr, 0) >= 0)
hasNeon = neon != 0;
}
#endif