There was a thread earlier this year on that very topic: https://mail.gnu.org/archive/html/lilypond-user/2021-06/msg00023.html
> On Jan 13, 2022, at 8:48 PM, Sam Gibson <samuelpgibso...@gmail.com> wrote: > > > Good day. > > I wish to use the Nashville Number System, using numbers in place of chord > names, for a simple lead sheet or chord chart. While it is possible to simply > enter and position chords using \lyricmode, I do not know of a way to include > the superscripts such as maj7 or sus4. Is there a way to use '\chords' and > replace the letter chord names with numbers? > > I am entering chords in the following way: > > \version "2.22.1" > \chords { c1 f:sus4 } > > I appreciate any assistance. > > Samuel Gibson