MacBook Air M4: zsh: permission denied and no common troubleshooting works

I don't have a definitive answer, I'm afraid. Some stuff to try that might help others to help.

It sounds to me as if Terminal either hasn't got access to the files or you are signed on as a different user.

Open System Settings, search for "Disk Access" and select "Allow applications to access all user files". In the RH pane make sure that Terminal has full disk access.

In Terminal make sure which ID is using Terminal with the command

id -un

It should be the same ID as the owner of the files you're trying to use.

Have you tried booting in recovery mode and trying access them via Terminal? It's worth a go.

The fact that your password doesn't work with sudo implies that either your account hasn't got admin rights or there's another account or that Root access is required to do what you want to do. Have you confirmed that your account has got admin rights? If it has then you can make sure you are logged in to Terminal as admin with

su <user name>

I can't remember how to enable the root account or if it's even possible these days. I do remember that it's not recommended to leave root access open, but it might help., It'll be quicker for you to google it than for me to do so and write it up.

Has this just started happening to files you previously had access to or is it the first time that you've tried to access them?

If it's the latter then have you recently copied them from somewhere else - such as a disc drive or another Mac?

If you look at the permissions of the files and folders in Finder what are they?

Exactly what type of file is this "TreeTagger" file?

From what you've shown in the screenshot, it appears you are trying to execute the TreeTagger file. If the file is not a script or binary executable compatible with macOS, then your command will not work.

As for the "sudo" password, your macOS user account must be an admin user account and not a standard user account unless an exception has been made to elevate that user's permissions/abilities.

Might not be related but I've had problems deleting stubborn files in the past. I know this isn't your exact problem but this thread helped eventually.

Removing stubborn files using Terminal no… - Apple Community

See HWTech's answer as the most cogent here. If TreeTagger is a file or folder, you have a certain naivety about UNIX syntax that needs to improve before you get into real trouble.