I tried to go inside the Resources file in the Contents of Pd-0.56-0.

1- I click on "pd" : answer of the Terminal:

Last login: Fri Aug  1 11:27:14 on ttys001
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd ; exit;
mauricemoncozet@Mac-mini-de-Maurice ~ % /Applications/Pd-0.56-0.app/Contents/Resources/bin/pd ; exit;


2- Click on pd-gui

Last login: Fri Aug  1 11:29:29 on ttys000
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-gui ; exit;
mauricemoncozet@Mac-mini-de-Maurice ~ % /Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-gui ; exit;
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-gui: line 18: /usr/local/lib/pd/tcl/pd-gui.tcl: No such file or directory
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-gui: line 18: exec: /usr/local/lib/pd/tcl/pd-gui.tcl: cannot execute: No such file or directory

Saving session...
...copying shared history...
...saving history...truncating history files...
...completed.

[Opération terminée]

3- click on pd-watchdog

Last login: Fri Aug  1 11:30:29 on ttys001
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-watchdog ; exit;
mauricemoncozet@Mac-mini-de-Maurice ~ % /Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-watchdog ; exit;
watchdog: signaling pd...
zsh: warning: 1 jobs SIGHUPed
zsh: hangup     /Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-watchdog

Saving session...
...copying shared history...
...saving history...truncating history files...
...completed.

[Opération terminée]

4- The command proposed by IOhannes m zmölnig

Last login: Fri Aug  1 11:39:33 on ttys001
mauricemoncozet@Mac-mini-de-Maurice ~ % /Applications/Pd-0.56-0.app/Contents/Resources/bin/pd -stderr -verbose
Pd-0.56.0 ("") compiled 00:36:10 Jul 30 2025
float precision = 32 bits
port 50221
"/Applications/Pd-0.56-0.app/Contents/Resources/../MacOS/Pd" 50221
Waiting for connection request...
... connected
input channels = 4, output channels = 4
MIDI input (Volt 476P) opened.
/Applications/Pd-0.56-0.app/Contents/Resources/bin/pd-watchdog
echo $?