Privacy from whom?
I ask because the easiest way to do what you’re asking is to have your local record store sell you shit and pay in cash (that you’ve laundered so the serial numbers don’t match the atm). You can even be like “I’m trying to get away from computers man, can you order me this off eBay?” And guaranteed if you spent a hundred bucks or so on used releases they’ll say “absolutely!”
Of course, you’ll stick out like a sore thumb and have a lie to keep up with, so you’ll not have any real measure of anonymity.
For the purposes of the average person the tech guy in your op is absolutely 100% correct.
All the platforms listed use transport encryption and that’s enough to avoid mitm surveillance which is enough for most people.
Most people’s “threat model” is the police or a pi. All the apps listed including signal have to comply with orders from American police and have “sidechain attacks” that involve stuff like getting some member of the groupchat’s device and scrolling up or tricking someone into giving up sensitive information.