The alerts is nice, though most of the rest (visitor centers, lesson plans) is static data and doesn't need to be an API, it can just be a static json file.

Campgrounds is also only providing static data. An "API" should show campsite availability and provide endpoints to book campsites to be useful as an API.

I was hoping to have API access to live bear collar tracking or some such. I'd love to create a system that auto-alerts me if a bear's motion path is intersecting my hike.