Try to copy amuled outside de app container:
cp /Applications/aMuleGUI.app/Contents/MacOS/amuled <OTHER_PATH>
xattr -cr <OTHER_PATH>/amuled
codesign -fs - <OTHER_PATH>/amuled
You will need XCode for the commands (I guess), but, after that:
$ <OTHER_PATH>/amuled
2021-02-13 08:49:53: Initialising aMuleD 2.3.3 compiled with wxBase(OSX Cocoa) v3.1.4
!2021-02-13 08:49:53: WARNING: The check for other instances is currently disabled in amuled.
!2021-02-13 08:49:53: Please make sure that no other instance of aMule is running or your files might be corrupted.
!2021-02-13 08:49:53: Attempting to use default directory at location
!2021-02-13 08:49:53: '/Users/<USER>/Library/Application Support/aMule/Temp'.
!2021-02-13 08:49:53: Attempting to use default directory at location
!2021-02-13 08:49:53: '/Users/<USER>/Library/Application Support/aMule/Incoming'.
2021-02-13 08:49:53: ListenSocket: Ok.
2021-02-13 08:49:53: Loading temp files from /Users/<USER>/Library/Application Support/aMule/Temp.
2021-02-13 08:49:53: All PartFiles Loaded.
2021-02-13 08:50:03: amuled: OnInit - starting timer
!2021-02-13 08:50:03: ERROR: aMule daemon cannot be used when external connections are disabled. To enable External Connections, use either a normal aMule, start amuled with the option --ec-config or set the key "AcceptExternalConnections" to 1 in the file ~/.aMule/amule.conf
2021-02-13 08:50:04: Now, exiting main app...
2021-02-13 08:50:04: aMule OnExit: Terminating core.
2021-02-13 08:50:04: aMule shutdown completed.
And then, you will need to setup the aMule config files as required by amuled.