Pilots are listed in the release notes. If interested in participating in a particular pilot, please submit a Salesforce Support case and ask Support to nominate/add you to the R&D Pilot Program record. Don't forget to include the desired org IDs.
Please suggest that Support @mention the Success Manager or your Salesforce Account team on your Program Engagement nomination record as an FYI.
Being nominated to a pilot doesn't mean that you will necessarily get into that pilot. Plan on completing some paperwork as well.
It's so worth it though to get early access to new or great functionality & features.