Are questions about availability of free and open source software for particular field of interest on topic? I mean questions like "Is there FOSS for controlling the Space Shuttle?" and more generally the type of question like this: "Is there FOSS for doing ABC?" (substitute an activity - like "autonomous driving", "quadcopter autopilot" etc.).
I think that would come under our existing close reason about off-site resources:
Questions that ask for off-site resources, or for a recommendation of an open source service or product are off-topic because they don't directly concern an issue related to open source development. See: What's wrong with "External Resources" questions? more information.
Asking whether there's software for a certain task would likely be construed as asking for an external resource, and would probably therefore be closed as off-topic. I can't see any easy way to rephrase it to bring it on-topic either, I'm afraid.
If you're looking for software for a specific purpose, and you have specific requirements for it, and you haven't been able to find it with your own research, you may be able to ask these questions at Software Recommendations. You can specify FOSS as one of the requirements. You should have a read of their question asking guidelines before asking there.