Time signature with note in denominator

To change the time signature from 3/2 to 3/(half note), override the 'stencil property to allow markup.

\version "2.24.0"

%% %% http://lsr.di.unimi.it/LSR/Item?id=554
%% see also http://lsr.di.unimi.it/LSR/Item?id=642

tsMarkup = \markup {
  \override #'(baseline-skip . 0.5)
  \column { \number 3 \note {2} #-1 }
}

\relative c' {
  \override Staff.TimeSignature.style = #'default
  \override Staff.TimeSignature.stencil = #(lambda (grob)
    (grob-interpret-markup grob tsMarkup))
  \time 3/2
  c2 d4 e f2
  g1.
}