Engineering only exists within industry. Everything else is a hobby.

That's simply not true. Engineering can exist outside industry. "Stuff costs money" is not a governing aspect of these kinds of things.

FOSS is the obvious counterexample to your absurdly firm stance, but so are many artistic pursuits that use engineering techniques and principles, etc.

Industry includes FOSS and artistic endeavors, anything that’s done professionally.

My intent was to exclude research efforts, which is fundamentally different from engineering, which is a practical concern and not a “get it to just work” concern.

That's an interesting question, the question of whether engineering per se is strictly pragmatic. I personally think drawing a hard line between research and engineering is a misstep and relies too heavily on a bureaucratic kind of metaphysics.