Microsoft has confirmed that Android will initially get ‘Share From' functionality, but this will later be followed with ‘Share To'. iOS functionality will be also be coming soon, but there's no indication of Share To functionality. Nearby Share has been available in Windows 10 since early Redstone 4 builds, allowing easier transfers over network.
The feature was demoed at Build 2018 but was lost among a number of bigger announcements. Overall, though, it fits into the theme of Microsoft's conference: cross-compatibility.
The Cross-Platform Push
Nearby Share will join Microsoft's Your Phone app to provide a significant unification of PC and mobile. The app will let users view and respond to messages, notifications, photos, and more directly from their Windows 10 PC. It will do so without use of the cloud, likely with a similar method to Nearby Share.
The result is going to be a much more unified experience, especially in combination with existing features. Users can already continue work on their PC, control apps, and will soon be able to view Timeline and browsing history on their phone.
However, like these features, the usefulness of Nearby Share hinges on developer support. They will have to add the integration into apps via the Project Rome SDK, enabling link and content sharing.
With the ease of use implications, I'm more optimistic about that support than previous integrations, but we'll just have to wait and see.