The final point that this isn't a technical problem, is a little off the mark.

The two pillars of data sovereignty are access and trust.

Te Pā Tūwatawata addresses both of these pillars. Data is encrypted in transit and at rest, access is controlled; it is built on open source technology, the platform can be audited and thus trusted.

Both pillars are fundamental, controlling access to data with strong encryption and effective governance ensures, control and ownership of IP, cultural knowledge, business critical information, etc... Whilst open source is not strictly required for trust of platforms, it does simplify things significantly (whilst generating it's own problems); ownership cannot be ensured, if you are unable verify the security is implemented correctly.

Both pillars are heavily technical in nature.