Don't know actually, it might be I they are just putting cloud-init in, installing their VM agents, and maybe like tweaking the bootloader setup and kernel cmdline or something. But equally, they might be compiling it themselves so they don't have to trust distros' build farms so much.

But anyway I don't think it matters. The hard part here is having a distro image supply chain, not compiling stuff. If they do need to start compiling loads of stuff they didn't before... They just need to add CPUs.