Comment by vk6

You actually can use FreeDoom if you want by loading it as a custom IWAD. If you visit the site's landing page (https://doompdf.pages.dev/) you can upload the IWAD file, and then it'll generate a new PDF file (that can even be saved and redistributed).

However, I chose the shareware version since the file size is a lot smaller and it's more recognizable to people.