Many such pieces of software exist both backed by non-profit foundations, and not. Before the Linux kernel was running the world, it was primarily maintained by volunteers. Also consider the myriad of Linux distributions that don’t have corp overlords. Or pick a *BSD. Or anything you watch video content with: ffmpeg, vlc, mpv. Or even various programming languages such as ECMA Script, Python, Ruby, C, C++, etc. Hell, even Lemmy fits into this category. There literally is a whole slew of software not directly backed by money and still maintained that literally runs the world.
I think “slur” also requires a component of direct offense for it mean anything. I don’t think it is valid to be offended for somebody else if that somebody else isn’t actually offended. If I make up a slur on the spot denigrating some aspect of your person that you do not find offensive (eg. Flumplenook - for a person who’s a bit clumsy), is it really a slur?
So if you call someone retarded, and they do not have the mental faculties to be offended, is it really a slur?
For slurs to have any meaning, any power, they need to be understood and internalized as offensive.