\boldsymbol doesn't work as expected inside equation environment

Question

I would like to obtain a bold equation inside an equation environment. I've tried

\begin{equation}
    \boldsymbol{x=y}
\end{equation}

but x=y is not rendered bold. What's going wrong here? If I write \boldsymbol{x=y} (without the surrounding equation environment), x=y is rendered bold as expected.

(Moreover, I would like to know how I can render an equation reference bold. I've tried \textbf{\eqref{eq:my-equation}} but again the text is not rendered bold.)

EDIT: Complete example compiled on overleaf with XeLaTex:

\documentclass{article}

\usepackage{amsmath, amsthm, amssymb, mathtools, thmtools, unicode-math}
\usepackage{hyperref, cleveref}

\begin{document}

\begin{equation}\label{eq:my-equation}
    \boldsymbol{x=y}
\end{equation}
\eqref{eq:my-equation}

\end{document}

Answer 1

with unicode-math \symbf selects a bold from the same font and as in classic latex \boldmath switches all math for to a bold font if it is available. Currently however there are not many bold unicode math fonts available and so you are limited to the bold math alphabet within the main font.

\documentclass{article}

\usepackage{amsmath, amsthm, amssymb, mathtools, thmtools, unicode-math}
\usepackage{hyperref, cleveref}

\begin{document}

\begin{equation}\label{eq:my-equation}
    x=y
\end{equation}
\eqref{eq:my-equation} \textbf{(\ref{eq:my-equation})}




\begin{equation}\label{eq:my-equation2}
    \symbf{x} \symbf{=} \symbf{y}
\end{equation}
\eqref{eq:my-equation2} \textbf{(\ref{eq:my-equation2})}


{\boldmath


\begin{equation}\label{eq:my-equation3}
    x = y
\end{equation}
\eqref{eq:my-equation3} \textbf{(\ref{eq:my-equation3})}
}

\end{document}
\end{document}

Answer 2

This will give bold math:

\documentclass{article}

\usepackage{amsmath, amsthm, amssymb, mathtools, thmtools, unicode-math}
\usepackage{hyperref, cleveref}

\begin{document}

\begin{equation}\label{eq:my-equation}
    \pmb{x=y}
\end{equation}

{\bfseries(\ref{eq:my-equation})}


\end{document}