AppleSeed is a version of the public beta testing program that’s invite only, making it more selective and limited than the open betas that are provided to all public beta testers. As AppleInsider notes, some AppleSeed members are now receiving invites for watchOS 6.
We are extending you an exclusive invitation to join the AppleSeed Program and to take part in shaping watchOS 6. As a participant, you’ll get to test-drive pre-release software and provide your feedback.
Our program also includes a community discussion board, questionnaires, and a Feedback Assistant application that lets you report any quality and usability issues you find, directly to Apple. Help us improve the quality of our next release and join today.
There’s no way to apply to be an AppleSeed member, so the watchOS 6 beta made available to AppleSeed participants will be limited in scale. Apple does not provide traditional watchOS public betas because there’s no way to downgrade the software installed on the Apple Watch. Most people will need to wait for the fall…
https://www.macrumors.com/2019/06/24/appleseed-members-watchos-6-beta/