\definelistextra[page][before=\page,after=\page]

\starttext

    \placelist[chapter,section][criterium=text,extras={1.1=page}]

    \chapter{x1}
    \section{xx1}
    \section{xx2}
    \chapter{y2}
    \section{yy1}
    \section{yy2}

\stoptext
