Inline math with double spacing

Question

I am using this solution by Bernard to have equations in display mode appear single-spaced in a double-spaced document. How can I achieve a similar result for inline math?

\documentclass{article}
\usepackage{lipsum}
\usepackage{amsmath}
\usepackage{physics}
\usepackage{fontspec}
\usepackage[doublespacing,nodisplayskipstretch]{setspace}
\usepackage{etoolbox}
\BeforeBeginEnvironment{align}{\begin{singlespace}\vspace{-\baselineskip}}
\AfterEndEnvironment{align*}{\end{singlespace}\noindent\ignorespaces}
\begin{document}
\lipsum[2]
\begin{align}
  Abc = DEF \
  DEF = Abc
\end{align*}
\lipsum[2]
Inline math: $\mqty(x\y)$
\end{document} 

Answer 1

It's better to set \jot to a negative dimension. Next, you can set \arraystretch to the reciprocal of \baselinestretch, which will affect array based objects.

\documentclass{article}
\usepackage{amsmath}
\usepackage{physics}
\usepackage[
  doublespacing,
  nodisplayskipstretch
]{setspace}
\usepackage{lipsum}
\setlength{\jot}{-4pt}
\renewcommand{\arraystretch}{0.6}
\begin{document}
\lipsum[2]
\begin{align}
  Abc = DEF \
  DEF = Abc
\end{align*}
\lipsum[2]
Inline math: $\mqty(x\y)$
\end{document}

Explanation: amsmath adds \jot to the interline spacing in its alignment environments.

Not that I endorse using physics; actually I recommend not using it.

If you want to also fix cases, load etoolbox and, in the document preamble, say

\makeatletter
\patchcmd{\env@cases}{1.2}{0.72}{}{}
\makeatother

Why 0.72? Because \env@cases does \renewcommand{\arraystretch}{1.2}, but we actually want it to be 1.2 times 0.6, which is the reciprocal of 1.667, the value of \baselinestretch for doublespacing.

If \onehalfspacing is used, it corresponds to a value 1.25 of \baselinestretch and the reciprocal to use is 0.8. For cases you need 0.96 instead of 0.72.