FYI, and for anyone else still learning how to version and cite code: Zenodo + GitHub is the most feature rich and user-friendly combination I've found.
I haven’t filed any NSF stuff (yet) but didn’t come across any such hard requirements where you had to commit to something like zenodo or else to archive the result of your research work for archiving/citations purposes.
Also, if you do bio-type research, you can use Data Dryad too!