ive not done secrets management before but i came across this list on hackernews, a few non-cloud ones use open source license https://news.ycombinator.com/item?id=37133054#37151218
but another user there have mentioned that while most of them integrate with Kubernetes and AWS, short lived DB credentials are not in any of those listed
seems like the author is frustrated that a place where the 1% of people who care about freedom over inconvenience cares more about freedom than the user experience of the 99%
its not like the poor user experience or being against joining large instances are to satisfy some egotistical whim. decentralization is hard, the fediverse still a work-in-progress and upcoming solutions (nomadic identities) would likely not be well received either
i dont think theyre equivalent tools since Terraform is used for things like creating cloud VMs with the selected OS image, configuring subnets and route tables among other things which i dont believe NixOS is meant for