Jonathan_Allen I am assuming you are referring to SQL best practices assessment for SQL Server enabled by Azure Arc. Today, database watcher does not support SQL Server enabled by Azure Arc. If there is interest in the customer community in adding that support, we strongly encourage everyone interested to leave feedback or vote on an existing feedback item if/when one is added.
Similarly, if there is customer interest in the assessment/insights/advisory features within database watcher, we ask that customers leave feedback and vote on existing feedback items. The likelihood of a feature being added is much higher when there is strong customer feedback requesting that feature.
Regarding early access, at this time we do not have any early access or private preview programs related to database watcher. However, if there is interest in a future participation, please send an email to dbwatcherfeedback [at] microsoft.com.