I've contributed to apple/swift and the Linux Kernel in the past, but testing the changes and building these projects might get frustrating sometimes. And to be honest I don't like C that much.
I have a few hours free per week and maybe someone here on hn might need some help on their oss/project.
Sure, you don't have to only contribute via GSoC. You can also contribute directly to them in your spare time which is how some of the contributors (not all) have done before being core developers.
Would you be interested in working on the browser based playground?