Inasmuch as a Unity developer, I don't understand why you didn't adapt Skybox to Pico4. I already made a video player for Pico4, based on AVProVideo asset (the one you use, I think) and it works fine. The Pico SDK is OK to me (but I might be wrong) it should be a few hours or days of development (for your team, not starting from scratch). You should hurry, as the Pico4 market is HUGE, and will be much more important in a near future, this headset has an AWESOME quality.
Best regards.