Yeah, no idea really. It'd be nice to find out from someone more in the know. Was the internet merely heavily deteriorated instead of shut down completely?

I also read that most of the VPNs wouldn't work, with the exception of psiphon.

They didn't fully shut down the internet the entire time. I.e. at least for a while, apparently port 80 was still open when other things were blocked.

I believe the Telegram app has a peer-to-peer feature that allows communication to be routed through other devices rather than requiring communication with the Telegram servers

That is not the case. It is a plain old client-server architecture.

You might be thinking of FireChat.