You're correct but in my experience everything I've used at a venue is analog, running almost entirely off of the mixing desk, without an external computer running Win/Mac/Linux. And half of these consoles I've used had a USB port which was used for, among other things, storing templates. This allowed for our front-of-house mix engineers and monitor mix engineers to cruise along because most of the work was done at home or in other venues. The software for writing those was Windows/Mac at the least, I don't know if any used Linux and I'm not sure if they were "human-readable" text formats.

At that price point I'm not so motivated to work on something FOSS, I care more for working with the hand-to-mouth musicians than the large institutions.