I haven't been able to find working examples. Here is some sample code. I
would really like to be able to use the light variation of this DIN-like
font.

\usemodule[fonts-variable]
\definefontfamily [mainface] [ss] [bahnschrift]
\setupbodyfont[mainface]

\starttext
\ss 123456789 Wild! \medskip

\startMPcode
picture pic;
pic := thelabel("This is in Metafont 0123456789", (0, 0));
draw pic;
\stopMPcode

\stoptext