Apple has released the third beta of macOS Catalina 10.15.1 to the developers

Overview
The macOS 10.15.1 SDK provides support for developing apps for Macs running macOS Catalina 10.15.1. The SDK comes bundled with Xcode 11.2 available from Beta Software Downloads. For information on the compatibility requirements for Xcode 11.2, see Xcode 11.2 Beta 2 Release Notes.

Apple Pay
Resolved Issues
Fixed an issue where Safari might stop responding when attempting to use Apple Pay on the Web. (56261377)

eGPU
New Features
Support has been added for the AMD Navi RDNA architecture.

Photos
New Features
You can now filter by Favorites, Edited, Photos, Videos or Keywords in the new All Photos view. (45589765)

You can now choose View > Metadata > Titles to enable titles and filenames in the new All Photos view. (48363059)

  macOS Catalina 10.15.1 Beta 3 released