Long story, but technically REX is still around but has not been able to continue to develop due to lack of funding and my cofounder and I needing to pay bills. We produced initial test silicon, but due to us having very little money after silicon bringup, most of our conversations turned to acquihire discussions.

There should be a podcast release (https://microarch.club/) in the near future that covers REX's history and a lot of lessons learned.