lualatex + unicode-math: bold style for italic latin/Latin/greek and upright Greek

Question

I use LuaLatex

I want this style: (0 for italic and 1 for upright)

      a A \gamma \Gamma
math  0 0    0      1
bold  0 0    0      1

but style=TeX provides:

      a A \gamma \Gamma
math  0 0    0      1
bold  1 1    0      1

and style=ISO provides:

      a A \gamma \Gamma
math  0 0    0      0
bold  0 0    0      0

I want to know how to set a style between these two.

\documentclass{article}

\usepackage{unicode-math}
\unimathsetup{mathbf=sym,math-style=ISO,bold-style=ISO}
\begin{document}
\[
    a A \gamma \Gamma
\]
\[
    \mathbf{a} \mathbf{A} \mathbf{\gamma} \mathbf{\Gamma}
\]
\end{document}

Answer 1

There is no official interface, but the styles are controlled by simple internal booleans:

\documentclass{article}

\usepackage{unicode-math}
\unimathsetup{mathbf=sym,math-style=ISO,bold-style=ISO}

\ExplSyntaxOn
\bool_gset_true:N\g__um_upGreek_bool
\bool_gset_true:N\g__um_bfupGreek_bool
\ExplSyntaxOff
\begin{document}
\[
    a A \gamma \Gamma
\]
\[
    \mathbf{a} \mathbf{A} \mathbf{\gamma} \mathbf{\Gamma}
\]
\end{document}

Answer 2

You didn't specified what macro over TeX you are using. If you are using OpTeX, then you can use \_rmgreek and \_rmGreek declarations in Unicode math:

\fontfam[lm]

% default: \_itvariables \_rmdigits \_itgreek \_rmGreek

$a, A, \gamma, \Gamma$,
$\boldmath a, A, \gamma, \Gamma$

\_itgreek \_itGreek  % ISO style

$a, A, \gamma, \Gamma$,
$\boldmath a, A, \gamma, \Gamma$

\_rmgreek \_rmGreek  % what you want:

$a, A, \gamma, \Gamma$,
$\boldmath a, A, \gamma, \Gamma$

\bye