Obtain small caps font from OpenType font when diffining a `\font`

Question

I’m using Erewhon font with the package fourier-otf. I would like to define a font with \font (to get it with the Lua fonction font.id) that is the small caps subpart of the regular font. Any ideas?

To be more precise, here some code

\documentclass{article}
\usepackage{fourier-otf}

\font\myfontSC={?????}

\begin{document}

\myfontSC Test

\end{document}

I want to use the \font command to be able to get the font id in the Lua side :

mynodeG.font=font.id("myfontSC")

Answer 1

Select the font inside a box and define \myfontSC to be the same font selector of the current font (which can be accessed as \the\font).

\documentclass{article}
\usepackage{fourier-otf}

\sbox0{\scshape \global\expandafter\let\expandafter\myfontSC\the\font}

\begin{document}

\texttt{\meaning\myfontSC}

\myfontSC Test

\end{document}

Answer 2

Can't you use the the command \newfontface?

\documentclass{article}

\usepackage{fourier-otf}
\newfontface\myfontSC{erewhon}[RawFeature={+smcp}]
\begin{document}
    
{\myfontSC Small Caps}

\scshape Test
    
\end{document}