There was apparently a Y-Combinator Research [0], and it seemed like HARC was maybe going to carry on the mantel of STEPS [1](the 20,000 lines-of-code complete operating system, GUI, and pretty much everything else) along with Alan Kay, etc.. But I don't see any activity beyond 2017 on the website.
[0] https://www.ycombinator.com/blog/harc
[1] https://tinlizzie.org/VPRIPapers/tr2012001_steps.pdf