Hi, I tried the tips given by Martin Tarenskeen and thought that a small
sample guide may be useful for other users.
Open PlayStore > search app Termux >
Open the terminal Termux and write: pkg install guile
Then write: pkg install lilypond
LilyPond 2.24.0 will be installed
Create a new directory: mkdir lilypond2.24
Create a new file: touch file1.ly
The directory where Termux put folder and file created is: data
/data/com.termux/files/home
but it is not visible from android file manager.
Open PlayStore and download Material Files and start it, give all
permissions.
Click the 3 dots at the top of dx to do "Add Storage > External Storage".
At this point the Termux folder appears. Open it and manipulate the
files. Once you open the folder "LilyPond2.24" do "Use this folder", and
from now on the folder path will appear in the side menu of Material Files.
Open the previously created file from here file1.ly and fill in the
lilypond code to compose the sheet music and save it.
From Termux terminal go to the director lilypond2.24 where is located
file.ly, then compile it from terminal: $ lilypond file.ly
Output a pdf in the same folder lilypond2.24 with the compiled sheet music.
I tested and it works.