You can do it easily if you do not want extreme typographic control and the user must himself install the wanted new fonts
- create the base image (=artwork and the non-editable background) as a single highres (=printable) JPG image.
- Use Photoshop, Indesign or other software to create a PDF that has your base image
- Open the PDF in Adobe Reader or Foxit Reader (=both freeware)
- Add some examples as comment textboxes and rudimentary drawings that can be created by the commenting tools. Textboxes use only installed fonts, so use some common system fonts.
Save your PDF. It's re-editable with the same PDF reader. It's re-editable also with the others, but you easily lose colors and font selections because they have different ways to present the comments.
This method is not for large scale business, only for discrete projects, because the user surely asks something about "how to get gorgeous fonts"
Non-Editability: If user has a print ready PDF, he also has a print-ready image of the artwork. That can be extracted and edited in a photo editor. Do not give your arwork as vector data, rasterize it before creating the PDF.
Not asked, but MS Office is another common software. It's inferior for pro quality printing, but home users could get few prints by using Word or PowerPoint. You could deliver templates with a background image and editable textboxes. This idea is given by user @Scott.
This answer can be improved. It needs a proper way to generate the base PDF with embedded (freeware) fonts in model textboxes and a way to force user's reader to utilitze them when editing the comments.