Honest question: why does it even matter the format source .sketch files are in? Kind of the whole point is that it's dead simple to export and share the finished assets; i.e., the sliced and compressed PNG / JPG files that developers need to build with. I don't know about your workflow but I definitely don't want someone messing with my assets! If there's something that isn't right or doesn't work, I can export and ZIP them up to send over in a jiffy. At that point, it makes no difference at all whether the recipient is working on Windows, Linux, stone tablets, etc.
Honest question: why does it even matter the format source .sketch files are in? Kind of the whole point is that it's dead simple to export and share the finished assets; i.e., the sliced and compressed PNG / JPG files that developers need to build with. I don't know about your workflow but I definitely don't want someone messing with my assets! If there's something that isn't right or doesn't work, I can export and ZIP them up to send over in a jiffy. At that point, it makes no difference at all whether the recipient is working on Windows, Linux, stone tablets, etc.