Is SPIFFS used? How?
Is there a simple example of a program that allows a user to open a PDF on the AP?

By default, about 1.5 MB of the onboard flash is allocated to SPIFFS.

 

What do you mean by "open a PDF on the AP"? How would that work?

The AP is just a network access device. Even if you are referring to a web server running on the same ESP32, what would you want the server to send to the client?

For useful help, please explain the application this will have. That is, explain the problem you expect this to solve. Also provide the configuration of the various parts involved.

You can almost certainly get hero with more information.

 

What do you mean

The AP GUI is opened. There is a button for a PDF user manual or PDF catalog or PDF of whatever. The user presses the button the GUI. The user should be able to view or download a PDF.

 

I guess you'd have to store the pdf on an SD or uSD card connected to the ESP32. Like this:
https://randomnerdtutorials.com/esp32-web-server-microsd-card/

 

The filesize is less than 1 Mb.

 

The AP GUI is opened. There is a button for a PDF user manual or PDF catalog or PDF of whatever. The user presses the button the GUI. The user should be able to view or download a PDF.

Essentially the browser renders the PDF transferred from the server:

Rendering PDF Files in the Browser with PDF.js | PSPDFKit

 

Is SPIFFS used? How?
Is there a simple example of a program that allows a user to open a PDF on the AP?

By default, about 1.5 MB of the onboard flash is allocated to SPIFFS.

Which programming environment are you using?

 

Arduino

 

Take a look at this library for ESP32. Read the documentation and the example code. Your httpd will read the file from the SPIFFS filesystem.