[cpx86]

When it comes to Wine, aren't they already doing this? Steam develops Proton in cooperation with CodeWeavers, who are the main sponsors of Wine, and parts of that work is upstreamed to the Wine project. The NTSYNC patch from what I can tell was also submitted by a CodeWeavers employee, so it doesn't seem far-fetched to say that Steam probably contributed to making this happen in Wine.

[BatteryMountain]

There are many other open source projects that gets used that never sees the spotlight like Wine does, but they are crucial too. Think audio codecs & processing, compression libs, networking libs, even sqlite. Our society depends on these projects too but there are too much friction for normal people to contribute to them (if they are even aware). Steam checkout is a low friction surface where normal people spend time. A small optional checkbox at the bottom with a two sentence explanation or link to a blog post to explain where the money goes, will add minimal new friction while giving people the opportunity to contribute to something meaningful. I think many gamers (esp adult ones) knows what open source means and they will actually contribute now & then. Fund allocations must be transparent (crucial!) so people can see where the money went.

[cpx86]

Oh absolutely, I would welcome some way of sponsoring such projects in general. I just meant to highlight that for this particular feature and project, there is already a form of sponsorship happening.