Was this a thing even a decade ago? AIX felt like it was in maintenance mode for much longer to me. From my limited perspective, it looked like the vast majority moved to just using Linux, maybe FreeBSD, and buying some batteries-included appliance for anything you couldn't easily self-host and maintain.
It's one of those things where nostalgic old Unix admins who's not really ready to embrace the anarchy of the Linux ecosystem is kind of pretending some clean old fashioned alternative exist, and cling to the myth that FreeBSD is more of an Unix(tm) Successor then Linux.
And yes i have also not really heard of greenfield Unix(tm) deployments since maybe 2008 and even then Linux was clearly where most people went when their old custom minicomputer(think DEC PDP 20, AS400 and HP3000) systems had to be replaced by something a bit more standardized.
SQLite has DO-178b certification that neither Oracle nor Db2 will ever obtain.
You can trust SQLite in avionics, not so with the others.
Avionics certification is an incredible milestone for FOSS in general.