Apple has seeded release candidates of macOS Sequoia 15.7 and macOS Sonoma 14.8.
A release candidate (RC), also known as gamma testing or “going silver”, is a beta version with the potential to be a stable product, which is ready to release unless significant bugs emerge.
Registered developers can download the release candidates via Apple’s developer portal. Or they can be downloaded over-the-air once the proper configuration profile has been installed from the Developer Center.