So the Unity SDK is odd. In addition to
Sam's link, the Unity SDK does some extra checking to simplify some of the developer flow (since it's really hard to call into Java code from C# -- you have to get super familiar with the JNI).
So the 7.2.0 Unity SDK is built off of the 7.3.0 C++ SDK. The 7.2.0 C++ SDK never got a Unity release. Numbers I echo below will be confusing without this disambiguation.
The 7.2.0 C++ SDK partially lifted the artificial dependency (the convenience layer) for Auth, Database, Functions, and Storage (see the patchset
here -- this is public). Some SDKs are missing, including Remote Config and Analytics.
This means that some features will work on a Fire device in the
7.2.0 Unity SDK, but not Analytics (it's not in the changelog, that's an unfortunate side effect for how the notes are generated). But if you are monitoring release notes, remember that the current mapping of Unity->C++ is one minor version behind. So a patch in C++ 7.3.1 will appear in Unity 7.2.1 (likely to persist until 8.0.0).
I don't have an ETA on if/when the additional missing SDKs will get patched in (even internally).