Today, Apple released iOS 12.4, macOS 10.14.6 Mojave, watchOS 5.3, and tvOS 12.4, minor updates that have been in testing for over two months. There's also an update available for the third-generation Apple TV.
There are a few new features, although all of the big stuff is reserved for iOS 13 and the other updates that will come alongside it. iOS 12.4 adds the ability to wirelessly transfer data from your old iPhone to your new one. There are some Apple News improvements, adding downloaded issues to the My Magazines section and adding News+ publications to the top of the News+ feed.
Another fix is a security fix. The Walkie-Talkie feature on watchOS was previously disabled due to a security issue that allowed someone to eavesdrop on you. That has been fixed, and the feature has been reactivated.
The release notes don't make any mention of Apple Card, a surprise considering that these updates were expected to enable support for it. Perhaps the groundwork is there and the feature can be turned on when Apple Card is released.