Problems with µ, displaying ţ with sisetup option (for combination of siunitx, fontspec and kpfonts)

This seems to work. The primary/only relevant? change is explicitly setting math-micro to \mu via \sisetup

\documentclass{article}
\usepackage{fontspec}
\usepackage[T1]{fontenc}
\usepackage[uprightgreeks,partialup]{kpfonts}


\usepackage{siunitx}

\sisetup{
    math-micro = \mu,
 }

\begin{document}
    \SI{1}{\micro \meter}

    \SI{1}{\micro \gram}

    \SI{1}{\kilo \gram}

    \SI{1}{\nano \gram}

    \si{\gram}

    \begin{equation}
    \frac{\partial Q}{\partial t} = \frac{\partial s}{\partial t} % just testing the partial ups
    \end{equation}

    \si{\micro \gram}
\end{document}