Re: U2413 Calibration DisplayCal/ArgyllCMS MacOS
Native gamut means that you use full gamut from your monitor, without limiting it to sRGB or AdobeRGB.
How you can limit one monitor's gamut? with a LUT3D or lut-matrix like our dell.
How? For our Dells each "emulated gamut primaries" like sRGB R,G&B primaries is a linear combination of native R,G&B. I mean sRGB Red "255" after calibration to sRGB is actually build with a portion or "true"/native blue, green and red in different quantity. Same for sRGB emulated geen and blue.
3 native combination for 3 emulated primaries = 3x3 matrix.
Native gamut is identity matrix since no other color gets mixed up.
... and DUCCS 1.6.5 has at last native gamut preset with custom gamma and custom whitepoint.
For photo editing LUT3D is not really needed. LUT3Ds are useful to emulate other screens or to a finer calibration in non color managed enviroments like video edition.
NEC has support for Macs sinec long time ago, but NEC calibration software is not free. You have to pay it. It's called SpectraviewII and some models(-SV2) have this software bundled (with the software cost applied to its price).
Your reports seem to be fine. If your displays have a "sufficient" color uniformity no need to change them.