One very interesting project built on OpenPOWER, but with unique vector extensions, is LibreSOC, https://libre-soc.org/. It promises to be fully open hardware as well.
I have very low confidence that it will ever be anything but vapour, given the project leader's previous record e.g. this project fully funded in August 2016 and not yet delivered 7 1/2 years later.
https://www.crowdsupply.com/eoma68/micro-desktop
The project updates (last one in 2020) are painful to read.
A competent outfit such as Pine64 or Sipeed can knock a project like this out in 6 months. They could have been subcontracted given the $234k raised.