https://wccftech.com/download-watchos-9-beta-1-for-apple-watch-series-7-6-5-4-se/

You can now download developer beta 1 of watchOS 9 update for your Apple Watch Series 7, 6, 5, 4, SE.

After taking a significant amount of time showcasing the features of its new software for Apple Watch, watchOS 9 beta is now available for download. If you are a registered developer with Apple (sign up here) then you too can take the latest software for a spin.