I’ve probably mentioned this before but I always wanted the Jedi of the Old Republic era to only have blue lightsabers. That way Luke’s ROTJ one has more significance. A potential opening scene cold be Luke in his X-wing. Flying near Yavin trying to salvage a Kyber crystal from the debris cloud of the Death Star. As he reaches out with the Force. Vader telepathically tries to contact him but he shrugs it off. A crystal fragment is found. Luke pulls it to the ship and Artoo captures it with his claw arm. It is green because of its prior use in the super laser. Palestine turns the crystal sacred to the Jedi into super weapon. Luke restores it.
Since the Death Star presumably ejected material throughout the Yavin system, it stands to reason that there could be crystal fragments on Yavin 4. Luke could go there in search of one.