question

>>Is it possible to segment players based on events in the Playstream?

No, segmentation is designed to let you create targeted groups of players based on their player properties, not events. A workaround for the example you proposed would be the following:

• Set up a new statistic (for instance, the name is “completed_onboard” ) that act as a flag to indicate whether players completed onboarding or not, for instance, when players completed onboarding, set the statistic to be 1, default is 0.
• While creating a new player segment, set the Statistics value filter to be the following:

Statistic value | completed_onboard | is | 1 |Latest version

Whenever a player completed onboarding and updated the statistic to be 1, he/she will enter the segment. Does this meet your requirements?

>> Also -- have you given any thought to enabling player segments as a filter (similar to Region) on the Trends page?

Referring to current Documentation and Blog posts, there seems to be no plan for this, however, you can make a feature request about it to help us improve the service here: https://community.playfab.com/spaces/24/index.html