Appimage is probably the most similar to a naked .exe in Windows. They are useful for small apps or simple indie games, but I prefer Flatpaks for my everyday big applications.
Agreed, Snaps are like Flatpaks but worse because locked down back end and Canonical’s sketchy nature. Imagine a really delicious pastry that anybody can make and sell, then imagine the same pastry but only one bakery in the world can make and sell it. Which would you prefer? Lol
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.