Nanos is an open-source unikernel: a minimal operating system that packages a single application into a small virtual machine. NanoVMs provides the OPS command-line tool for building and running unikernels, and it deploys them to public clouds such as Google Cloud, AWS, Azure, Vultr and DigitalOcean. NanoVMs also sells subscriptions, package hosting, support and consulting. The Nanos kernel is published under the Apache 2.0 licence, while the builds NanoVMs supplies are not open source.
NanoVMs Inc. is a US company, as its copyright notice on the website shows. Its paid services and package hosting fall under US jurisdiction, which matters for CLOUD Act exposure. For a European organisation the open-source kernel and tooling can run on infrastructure the organisation chooses, but the paid builds and hosted package repository should be assessed against the vendor's own data handling terms.