This isn't really true. I know that both Google and Amazon (and likely others) have their own versions of desktop Unbuntu, and, importantly, all software comes

This isn't really true. I know that both Google and Amazon (and likely others) have their own versions of desktop Unbuntu, and, importantly, all software comes from their own PPAs (including OS / kernel updates). In terms of the "kill switch" threat, this pretty much removes it. Additionally, desktop Linux systems are similar and open enough that it wouldn't be a big deal to move to Debian / others if Canonical went up in smoke or were compromised. It certainly wouldn't cost end users file compatibility.