Spacing of ordinary atoms in mathmode

Is there a way to generically enlarge the spacing between simple symbols in mathmode (not asking for spacing around operators nor for individually applying commands such as \! for each whitespace)? Microtype's \textls{} and \lsstyle seem to only work for textparts of an equation.

\documentclass{article}
\usepackage{mathtools}
\usepackage{microtype}

\begin{document}
$\displaystyle \hat{H} = \frac12 m\omega_\text{m}^2 \hat x_\text{m}^2+\frac{\hat p_{\text{m}}^2}{2m}$

\textls[500]{%
$\displaystyle \hat{H} = \frac12 m\omega_\text{m}^2 \hat x_\text{m}^2+\frac{\hat p_{\text{m}}^2}{2m}$
}
\end{document}


To further clarify, I am looking for a way to modify the space between ordinary atoms as they seem to be called.

Check the Herbert Voss's beautiful explanation about mathmode, https://ctan.org/pkg/voss-mathmode?lang=en and refer page number 30 about spacing in math by using the tags \thinmuskip, \medmuskip, and \thickmuskip