I'm not sure a data center run by ... Palantir of all organizations is what people have in mind when they worry about data sovereignty.

They are selling it, not running it.

It is just a dedicated computer system, which should be managed by its owner, like any other on-prem servers.

I doubt that it has a good price/performance ratio, but it is a solution for those who feel that they do not want to search, buy, assemble, install and configure every HW/SW component.