Well, I have a Kindle Fire HD 10 which includes a camera, and the ability to read PDFs as well as books and so on. And I have it set up so that it only works on WiFi, no data connection.
But it's definitely a tablet, (and I have used it as sort of a "poor man's laptop" with the keyboard I bought for it.) rather than a device just for PDFs and pictures. 10" is a bit bulky too for what it sounds like you want it to do, but there are smaller ones that also have cameras. And unlike other tablets they're less than $100.00, most giving you a choice between cellular data connection or not.