I can finally get non-bold sans serif Greek, but is there a better way?

I am trying to make a package that fully implements ISO 80000-2 notation recommendations for use in a physics book I am planning to write. These recommendations call for sans serif letters to represent tensors, for which bold is perfect when using coordinate-free notation. Unicode easily accommodates this. However, in physics many tensors (particularly in electromagnetic theory) are represented by Greek letters. Non bold (which I believe is called medium weight…correct me if I am wrong) characters are typically used in tensor index notation, and Unicode doesn’t officially provide them. This is problematic in physics because many tensors in electromagnetic theory (e.g. Levi-Civita, permittivity, permeability, susceptibility, polarizability) are notated with Greek letters and thus can’t be accommodated by the ISO 80000-2 recommendations. I am not going to argue whether or not ISO 80000-2 is correct, or even necessary, mostly because my arguments will carry very little weight. I want to implement very internally consistent notation in my work as easily as possible, thus my question.

Thanks to David Carlisle I recently learned that the STIX Two Math font includes the otherwise missing characters in the Private Use Area. The mwe shows the admittedly clumsy way I am currently accessing the necessary glyphs. My question is whether or not there is a better way to do it what will work well with ‘unicode-math.’

The MWE:

% !TEX program = lualatexmk
% !TEX encoding = UTF-8 Unicode

documentclass{article}
usepackage{geometry}
usepackage{mathtools}
usepackage{unicode-math}
unimathsetup{math-style=ISO}
unimathsetup{warnings-off={mathtools-colon,mathtools-overbracket}}
setmathfont[Scale=MatchLowercase]
  {Latin Modern Math}    % default math font; better J

setmathfont[Scale=MatchLowercase,range={"E17C-"E1F6}]{STIX Two Math}
newfontfamily{symsfgreek}{STIX Two Math}

% I don't understand why text{...} is necessary.
newcommand{symsfupalpha}      {text{symsfgreek{^^^^e196}}}
newcommand{symsfupbeta}       {text{symsfgreek{^^^^e197}}}
newcommand{symsfupgamma}      {text{symsfgreek{^^^^e198}}}
newcommand{symsfupdelta}      {text{symsfgreek{^^^^e199}}}
newcommand{symsfupepsilon}    {text{symsfgreek{^^^^e1af}}}
newcommand{symsfupvarepsilon} {text{symsfgreek{^^^^e19a}}}
newcommand{symsfupzeta}       {text{symsfgreek{^^^^e19b}}}
newcommand{symsfupeta}        {text{symsfgreek{^^^^e19c}}}
newcommand{symsfuptheta}      {text{symsfgreek{^^^^e19d}}}
newcommand{symsfupvartheta}   {text{symsfgreek{^^^^e1b0}}}
newcommand{symsfupiota}       {text{symsfgreek{^^^^e19e}}}
newcommand{symsfupkappa}      {text{symsfgreek{^^^^e19f}}}
newcommand{symsfuplambda}     {text{symsfgreek{^^^^e1a0}}}
newcommand{symsfupmu}         {text{symsfgreek{^^^^e1a1}}}
newcommand{symsfupnu}         {text{symsfgreek{^^^^e1a2}}}
newcommand{symsfupxi}         {text{symsfgreek{^^^^e1a3}}}
newcommand{symsfupomicron}    {text{symsfgreek{^^^^e1a4}}}
newcommand{symsfuppi}         {text{symsfgreek{^^^^e1a5}}}
newcommand{symsfupvarpi}      {text{symsfgreek{^^^^e1b3}}}
newcommand{symsfuprho}        {text{symsfgreek{^^^^e1a6}}}
newcommand{symsfupvarrho}     {text{symsfgreek{^^^^e1b2}}}
newcommand{symsfupsigma}      {text{symsfgreek{^^^^e1a8}}}
newcommand{symsfupvarsigma}   {text{symsfgreek{^^^^e1a7}}}
newcommand{symsfuptau}        {text{symsfgreek{^^^^e1a9}}}
newcommand{symsfupupsilon}    {text{symsfgreek{^^^^e1aa}}}
newcommand{symsfupphi}        {text{symsfgreek{^^^^e1b1}}}
newcommand{symsfupvarphi}     {text{symsfgreek{^^^^e1ab}}}
newcommand{symsfupchi}        {text{symsfgreek{^^^^e1ac}}}
newcommand{symsfuppsi}        {text{symsfgreek{^^^^e1ad}}}
newcommand{symsfupomega}      {text{symsfgreek{^^^^e1ae}}}
newcommand{symsfupDelta}      {text{symsfgreek{^^^^e180}}}
newcommand{symsfupGamma}      {text{symsfgreek{^^^^e17f}}}
newcommand{symsfupTheta}      {text{symsfgreek{^^^^e18e}}}
newcommand{symsfupLambda}     {text{symsfgreek{^^^^e187}}}
newcommand{symsfupXi}         {text{symsfgreek{^^^^e18a}}}
newcommand{symsfupPi}         {text{symsfgreek{^^^^e18c}}}
newcommand{symsfupSigma}      {text{symsfgreek{^^^^e18f}}}
newcommand{symsfupUpsilon}    {text{symsfgreek{^^^^e191}}}
newcommand{symsfupPhi}        {text{symsfgreek{^^^^e192}}}
newcommand{symsfupPsi}        {text{symsfgreek{^^^^e194}}}
newcommand{symsfupOmega}      {text{symsfgreek{^^^^e195}}}

newcommand{symsfitalpha}      {text{symsfgreek{^^^^e1d8}}}
newcommand{symsfitbeta}       {text{symsfgreek{^^^^e1d9}}}
newcommand{symsfitgamma}      {text{symsfgreek{^^^^e1da}}}
newcommand{symsfitdelta}      {text{symsfgreek{^^^^e1db}}}
newcommand{symsfitepsilon}    {text{symsfgreek{^^^^e1f1}}}
newcommand{symsfitvarepsilon} {text{symsfgreek{^^^^e1dc}}}
newcommand{symsfitzeta}       {text{symsfgreek{^^^^e1dd}}}
newcommand{symsfiteta}        {text{symsfgreek{^^^^e1de}}}
newcommand{symsfittheta}      {text{symsfgreek{^^^^e1df}}}
newcommand{symsfitvartheta}   {text{symsfgreek{^^^^e1f2}}}
newcommand{symsfitiota}       {text{symsfgreek{^^^^e1e0}}}
newcommand{symsfitkappa}      {text{symsfgreek{^^^^e1e1}}}
newcommand{symsfitlambda}     {text{symsfgreek{^^^^e1e2}}}
newcommand{symsfitmu}         {text{symsfgreek{^^^^e1e3}}}
newcommand{symsfitnu}         {text{symsfgreek{^^^^e1e4}}}
newcommand{symsfitxi}         {text{symsfgreek{^^^^e1e5}}}
newcommand{symsfitomicron}    {text{symsfgreek{^^^^e1e6}}}
newcommand{symsfitpi}         {text{symsfgreek{^^^^e1e7}}}
newcommand{symsfitvarpi}      {text{symsfgreek{^^^^e1f5}}}
newcommand{symsfitrho}        {text{symsfgreek{^^^^e1e8}}}
newcommand{symsfitvarrho}     {text{symsfgreek{^^^^e1f4}}}
newcommand{symsfitsigma}      {text{symsfgreek{^^^^e1ea}}}
newcommand{symsfitvarsigma}   {text{symsfgreek{^^^^e1e9}}}
newcommand{symsfittau}        {text{symsfgreek{^^^^e1eb}}}
newcommand{symsfitupsilon}    {text{symsfgreek{^^^^e1ec}}}
newcommand{symsfitphi}        {text{symsfgreek{^^^^e1f3}}}
newcommand{symsfitvarphi}     {text{symsfgreek{^^^^e1ed}}}
newcommand{symsfitchi}        {text{symsfgreek{^^^^e1ee}}}
newcommand{symsfitpsi}        {text{symsfgreek{^^^^e1ef}}}
newcommand{symsfitomega}      {text{symsfgreek{^^^^e1f0}}}
newcommand{symsfitDelta}      {text{symsfgreek{^^^^e1c2}}}
newcommand{symsfitGamma}      {text{symsfgreek{^^^^e1c1}}}
newcommand{symsfitTheta}      {text{symsfgreek{^^^^e1d0}}}
newcommand{symsfitLambda}     {text{symsfgreek{^^^^e1c9}}}
newcommand{symsfitXi}         {text{symsfgreek{^^^^e1cc}}}
newcommand{symsfitPi}         {text{symsfgreek{^^^^e1ce}}}
newcommand{symsfitSigma}      {text{symsfgreek{^^^^e1d1}}}
newcommand{symsfitUpsilon}    {text{symsfgreek{^^^^e1d3}}}
newcommand{symsfitPhi}        {text{symsfgreek{^^^^e1d4}}}
newcommand{symsfitPsi}        {text{symsfgreek{^^^^e1d6}}}
newcommand{symsfitOmega}      {text{symsfgreek{^^^^e1d7}}}

begin{document}

( symsfupalphasymsfupbetasymsfupgammasymsfupdeltasymsfupepsilonsymsfupvarepsilonsymsfupzeta
   symsfupetasymsfupthetasymsfupvarthetasymsfupiotasymsfupkappasymsfuplambdasymsfupmusymsfupnu
   symsfupxisymsfupomicronsymsfuppisymsfupvarpisymsfuprhosymsfupvarrhosymsfupsigma
   symsfupvarsigmasymsfuptausymsfupupsilonsymsfupphisymsfupvarphisymsfupchisymsfuppsi
   symsfupomegasymsfupDeltasymsfupGammasymsfupThetasymsfupLambdasymsfupXisymsfupPisymsfupSigma
   symsfupUpsilonsymsfupPhisymsfupPsisymsfupOmega )


( symsfitalphasymsfitbetasymsfitgammasymsfitdeltasymsfitepsilonsymsfitvarepsilonsymsfitzeta
   symsfitetasymsfitthetasymsfitvarthetasymsfitiotasymsfitkappasymsfitlambdasymsfitmusymsfitnu
   symsfitxisymsfitomicronsymsfitpisymsfitvarpisymsfitrhosymsfitvarrhosymsfitsigma
   symsfitvarsigmasymsfittausymsfitupsilonsymsfitphisymsfitvarphisymsfitchisymsfitpsi
   symsfitomegasymsfitDeltasymsfitGammasymsfitThetasymsfitLambdasymsfitXisymsfitPisymsfitSigma
   symsfitUpsilonsymsfitPhisymsfitPsisymsfitOmega )


end{document}