One option for Capstone is to do a "stand-alone" presentation. By "stand-alone" we mean using a tool such as Google Slides to convey your information, without presenting it in person. "Stand-alone" means the presentation has to teach the viewer about your topic, convey your learning, without you there to verbalize the experience.
Whereas an in-person presentation will have a few, minimal, clean slides a "stand-alone" presentation will be much more detailed and will include far more slides than an Ignite or TED presentation. The presentation has to tell your story without you being there.
As 5th graders you have done similar things in the past with the rocketry unit.
Here are a few examples of "stand-alone" presentations that convey the experience without the need for someone to personally present it: