I am at it again... :)
Using the http://github.com/khaledhosny/euler-otf/blob/master/euler.otf font, can one kern distance between T and P with Lualatex?
Clearly, my attempt does not work...
Could it perhaps be that the used glyphs are not called T and P?
\documentclass{standalone}
\usepackage{filecontents}
\begin{filecontents*}{mykern.fea}
languagesystem DFLT dflt;
languagesystem latn dflt;
feature kern {
pos T P 200;
} kern;
\end{filecontents*}
\usepackage{fontspec}
\usepackage{unicode-math}
\setmathfont[math-style=upright,FeatureFile=mykern.fea]{euler.otf}
\usepackage{microtype}
\usepackage{siunitx}
\begin{document}
$TP$
\end{document}