Similar tactic among all the large tech corpos, switch focus to IaaS, PaaS, SaaS, become the backbone of the modern computing landscape.
It’s basically a slow switch to becoming critical international infrastructure like power grids, water ways, and gas/oil pipelines.
This all while locking you in as much as possible and milking as much value as they can squeeze.
I’ve heard that the DoD uses RHEL pretty extensively. RHEL in the US Military
That article says that the US military has the largest single install base for RHEL in the world, but that was about 15 years ago, I don’t know if that’s still true.
Apparently back then the US nuclear sub fleet and its sonar systems also ran on RHEL.
I suspect lots of military hardware runs some form of *Nix or BSD type system. Many embedded systems run some *Nix type OS, and a huge portion of the developed world’s weaponry is smart, so it it full of low power embedded systems and custom SoCs.