Add some extra kerning behind letters in math mode in beamer metropolis

Question

This is MWE:

% !TEX program = xelatex
\documentclass{beamer}
\usetheme[numbering=fraction,block=fill]{metropolis}
\setsansfont{Fira Sans Book}[BoldFont=Fira Sans SemiBold,Scale=0.95]
\usepackage{bm}

\begin{document}
\begin{frame}{A frame}
\[ \sqrt{T} \quad \frac{1}{T} \quad \bm{X}\bm{X}' \]
\end{frame}
\end{document}

And this is the ouput:

Clearly, the capital T looks too wide compared to the square root and the fraction lines. As for the bold X's, they just stay too close, and the prime is also too close to the right X.

Adding a small kerning behind these letters would achieve what I want:

\[ \sqrt{T\mkern1mu} \quad \frac{1}{T\mkern1mu} \quad \bm{X\mkern1mu}\bm{X\mkern1mu}' \]

which produces

So is there a simple way to define such kerning so that I don't have to type those \mkerns?