When your code is open then yes, you are giving your time and energy and yes, you are being generous, but also other people become dependent on you and your understanding of the codebase. I think making a codebase Open Source is a commitment. If you want to give your time but are not ready for a major commitment, maybe join another project and contribute in that way, but don't pollute the global namespace with a half-commitment on a project that should remain a private repository, at least find some collaborators and think long-term.