My friend has a fatalistic view of privacy. How true are his claims?

I've been discussing the topic of privacy with friends and family lately, after just recently realizing how ambivalent I had been about it. A friend of mine seems to think that it's useless to seek privacy online, but the reasons he cites are quite shocking if true. I'm definitely no expert when it comes to IT, but I'm not clueless either. However, I am not informed enough about the current state of technology--particularly concerning tracking--to know how true my friend's claims are. I was hoping some of you could give me perspective on what he's been talking about.

First, he claims that, no matter what, our devices are communicating with all other devices within our proximity and leaking data without our knowledge or permission. He gave the example that when you purchase something with a card at a store, your purchase info is automatically cross-referenced with data on your phone and supplied to advertisers. To me, it seems like this sort of thing (Facebook advertising about things you've done and talked about elsewhere) is due more to user data being collected, shared, and tracked among various services like Facebook or Google. He seems convinced that all wifi-enabled devices are automatically connected to a network even when the device says it is not. I don't know how this would be possible. The phenomenon he is attributing to devices automatically connecting to nearby networks (which ones? simultaneously? how?) seems like it is better explained by the various tracking and surveillance technologies notoriously implemented by "services" such as Facebook.

Second, he seems to think the only way to have true privacy is to make a network completely disconnected from other networks. This seems obviously true, but he is saying this because he believes there is nothing you can do to be anonymous or protect yourself other than being physically isolated. He cites Musk and/or Zuckerberg's secure networks that use sea drones and satellites (but I have no idea what he's referring to).

Third, (this one seems patently false, but I'll include it anyway) he rejoined my claims about open source being the only real option for privacy by saying that any open source phone OS would be compromised as soon as it was released, and that a secure open source OS would only be a real possibility once neural net processors become cheap in the next few decades.

What do you guys make of this? My impression is that he is not very informed and/or gets information from sources that spread false information or attribute everything to grandiose conspiracy theories. Maybe he knows way more than me, but his claims seem wildly out of line with what I've been learning about privacy these past few weeks.