Don't hold your breath, these rumors have been going for well over a decade:
2018: "The current owner of Symbolics displayed interest in open-sourcing Genera a few years ago but nothing happened since then." https://news.ycombinator.com/item?id=17824330
2014: "The problem is that the Symbolics IP is now owned by John Mallery; he has stated he has plans for making it available but so far (several years) has not yet done so." https://news.ycombinator.com/item?id=7882034
The software itself can easily be found these days, if you're interested for hobbyist reasons.
> The software itself can easily be found these days
where?
Good article on getting things set up: https://archives.loomcom.com/genera/genera-install.html
An old, messy automation: https://github.com/ynniv/vagrant-opengenera