[supar]

If you are not familiar with Linux (for example, you're working on Windows or mostly doing web-development), it could entirely be. Mac OS is more friendly, but I certainly saw many developers that didn't scratch the surface and directly went with XCode/ObjC/iOS. In that sense, you can build a career without ever considering OSS development/usage.

What's best for somebody that, as of now, is questioning which project should be looking at? If you don't know what you're looking for, any advice is just as good as a google or github search (ie: useless).

If you start by having fun, even by publishing your random projects, you will be dragged in by dependencies (that's ironic). I would rather recommend choosing something fun to work with than a random project to look at.