Although the annual NASA SpaceApps hackathon is now run by NASA's Earth Science Division and not Office of the Chief Information Officer's Open-Innovation program, Open-innovation still has close ties to SpaceApps due to the Open-Innovation sites being a common place people go to get NASA datasets, code, and APIs that they use in their SpaceApps projects.
Recently, Justin Gosses presented these google slides summarizing the NASA data universe for a SpaceApps group in the Ukraine.
Topics included an introduction to open-innovation data sites, why so many data sites, harvesting relationships between data sites, as well as tips for searching for NASA datasets. If you're building a project that uses NASA data, and you don't know where to start, it might be worth your time to go through the slides. There are many links that go to different parts fo the NASA data universe as well as suggestions for how to use external sites and resources to find starter code for working with NASA data.