You want, ideally a crosscut shredder. Burning even moderate amounts of paper indoors is probably too much of a fire or smoke inhalation risk, unless you already have a fireplace you can use.
Mix the sensitive documents with pages from unrelated useless documents (could be scratch paper notes, old letters or homework, junk mail, paper advertisements or pages from catalogs or even a phonebook) and shred all that stuff together.
After shredding, seperate the shredded paper into bags so that no one "document" is likely to be able to be reassembled from one bag. Throw the bags away in separate places and/or on separate days. Drop them in different dumpsters behind businesses or different trashcans in the park. Alternatively if you can store the shredded paper in bags at a secure location, you can save it up and then take it on a camping trip and burn it in your campfire.
If your threat model is so severe that these methods aren't secure enough, consider instead avoiding writing or printing the information in the first place.
I have not messed with media streaming from a Pi to a TV since the 3B, which was a laggy experience that resulted in overheating.
For that reason, hardware-wise I would recommend at least a Pi4 with some kind of cooling solution. Could be a passive metal radiative case, or active fan cooling.