In the 2022 annual financial statement they do mention expanding to the US, though they don't go into the legal details. As the link posted in the cousin comment mentions, though:
> Hetzner US LLC, as a subsidiary of Hetzner Online GmbH, provides data center services within the USA for the parent company, Hetzner Online.[2]
So there is no US owner.
[0]: https://www.northdata.de/Hetzner+Online+GmbH,+Gunzenhausen/A...
[1]: https://www.unternehmensregister.de/ (enter "ENSoXX Holding AG" in the text field)
[2]: https://docs.hetzner.com/general/general-terms-and-condition...