Problem with passing options through customized class interface myclsset using pgfkeys

My intention is to create a class with a interface setup command myclsset

documentclass{myclass}

myclsset{key1=val1, key2=val2, ..} % key-value list

begin{document}
...
end{document}

where myclsset, acting as document interface, can be smoothly used anywhere after documentclass{} call. I choose pgfkeys to implement for some specific reasons.

Here’s the .cls file, in which I try to create a choice key whose value is a boolean if switch that does formatting work for me:

NeedsTeXFormat{LaTeX2e}
ProvidesClass{myclass}[2019/03/27 My Test Class]

RequirePackage{pgfkeys,pgfopts}

newififmyclass@section@italic
pgfkeys{%
   /myclass/.cd,
   section/.is choice,
   section/italic/.code = {myclass@section@italictrue}
}

% Set up the interface for the document class.
newcommand*{myclsset}[1]{%
   pgfqkeys{/myclass}{#1}%
}

DeclareOption*{PassOptionsToClass{CurrentOption}{article}}
ProcessOptions

ProcessPgfOptions{/myclass} % Processing options through pkg/class

LoadClass{article} % Load base class

RequirePackage{titlesec} % Load a package

ifmyclass@section@italic
   titleformat*{section}{itshape} % make section title italic
else
   relax
fi
endinput

The MWE shows that documentclass[...]{myclass} can work:

documentclass[section = italic]{myclass}

begin{document}
section{A Topic}
end{document}

However, this pattern:

documentclass{...}
myclsset{...} % key-value list in braces

does not work at all:

documentclass{myclass}

myclsset{section = italic}

begin{document}
section{A Topic}
end{document}

The section title does not switch to italic. So the question is what do I miss to fail to make myclsset work?

newcommandmyclass@handle@keys{%
    ifmyclass@section@italic
        titleformat*{section}{itshape} % make section title italic
    else
        relax
    fi
}
AtBeginDocument{myclass@handle@keys}