It wasn't linked to Darpa but it was developed as an experimental project by an autonomous team in South African office lead by Chris Pinkham and initially Amazon were quite secretive about it.

"""The designation "skunk works" or "skunkworks" is widely used in business, engineering, and technical fields to describe a group within an organization given a high degree of autonomy and unhampered by bureaucracy, with the task of working on advanced or secret projects. """

https://www.zdnet.com/article/how-amazon-exposed-its-guts-th...

https://en.wikipedia.org/wiki/Skunk_Works#:~:text=The%20desi....

Amazon EC2 was developed mostly by a team in Cape Town, South Africa led by Chris Pinkham. Pinkham provided the initial architecture guidance for EC2 and then built the team and led the development of the project along with Willem van Biljon.

with links to a Register piece

https://www.theregister.com/2010/06/25/nimbula_cloud_os/

And

https://web.archive.org/web/20100621120705/http://itknowledg...