How to get a sans-serif math wide hat in {xe|lua}latex?

Feeding

\documentclass{standalone}
\usepackage{unicode-math}
\begin{document}
$$\widehat{\strut~~~\,\,\,\ \ \ \mskip10mu\mkern10mu\strut}$$

$$\mathsf{\widehat{\strut~~~\,\,\,\ \ \ \mskip10mu\mkern10mu\strut}}$$
\end{document}


to xelatex produces

and feeding it to lualatex results in

As you notice, the sans-serif hat is narrow in both cases whatever junk you put inside. How to produce a wide hat (without anything under it) in the scope of \mathsf{...}? Here, we don't really want an accent, but only a decently wide hat (say, 1em) as a symbol in a sans-serif math font.

Just go back to \mathnormal first:

\documentclass{standalone}
\usepackage{unicode-math}
\begin{document}
$$\widehat{\strut~~~\,\,\,\ \ \ \mskip10mu\mkern10mu\strut}$$

$$\mathsf{\widehat{\strut~~~\,\,\,\ \ \ \mskip10mu\mkern10mu\strut}}$$

$$\mathsf{\mathnormal{\widehat{\strut~~~\,\,\,\ \ \ \mskip10mu\mkern10mu\strut}}}$$
\end{document}