MacBook Pro 13″ stuck on Statefulfirewall installation screen

If all else fails you can check to see if you've removed all of the supporting files by downloading and running the shareware app Find Any File to search for any files with the application's or the developer's name in the file name.  For XXXX software you'd do the following search(es): 

1 - Name contains XXXX

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

If you get warnings that the file can't be deleted because it is in use or used by another app boot into Safe Mode according to How to use safe mode on your Mac and delete from there.

Note:  if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode.  This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.

If FAF application may have found the bits and pieces of the software but it may require using the method in the below link.

If you are not comfortable doing this - DO NOT Attempt

One wrong move in this state and it could be very bad for the computer

Disabling and Enabling System Integrity Protection - Apple ..

The moment you are finished Re-Enable SIP

Hi Gottmeinwasist,

We'd recommend the following third-party tool Malwarebytes, Mac Virus Scan | 2023 Mac Antivirus and Anti-Malware, which can help remove unwanted items, including adware and other unwanted software. For questions about Malwarebytes, you can contact their support team.

Cheers.

As Old Toad suggested, I strongly recommend Malwarebytes. Remove any anti-virus like Avast. Go to a Finder window and click search on top. Search for "statefulfirewall". In that same Finder window, click the + button under the search field and where it says Kind, change it to System Files, and then "are included".

Delete all files related to statefulfirewall. If you are unable to delete them here, boot into Safe Mode.

Malwarebytes will list files launched at startup that could be causing your problems.

https://malwaretips.com/blogs/remove-statefulfirewall/