[Someone]

“but for some reason it has fallen to the states to provide apps that work with those APIs”

https://developer.apple.com/contact/request/download/Exposur... gives you that reason:

“In order to use the Exposure Notification APIs, You must be a government entity, such as a government health services organization, or a developer who has been endorsed and approved by a government entity to develop an Application on behalf of a government for COVID-19 response efforts. Entitlement Profile(s) are limited to one (1) Application per country unless the country has a regional approach, or as otherwise agreed by Apple.”