I doubt much will end up public, as most vpns have a zero retention policy, so that leaves the NSA being able to track things at a lower level.
All you need a Raspberry Pi and some public Wi-Fi network to create a jump point and hide among the 100s of devices going on and off that one public IP. With projects like TailScale you could set it up and plant it somewhere in a matter of hours
I thought most VPNs sold usage data to ad companies?
I also recently wrote a single ephemeral socks5 proxy over a hidden service in Rust. Since they’ve probably compromised other machines in the past, they could’ve easily used something similar to proxy their connection through tor and to some random computer (access some vulnerable router through tor, proxy through it, etc). Hiding your tracks aren’t hard