How to get the Twinkle Twinkle Trophy/Achievement
To get the Twinkle Twinkls trophy/achievement you need to release a firefly in your settlement. In Assassin's Creed: Valhalla Fireflies spawn at night in the building shown in the video below so it must be nighttime before you attempt this trophy/achievement.
Enter the building, run after the firefly (glowing flying dot), and pick it up by pressing the interaction button (Triangle on PlayStation and Y on Xbox) on your controller. If you caught the firefly it will say '+1 Firefly' on the right side of the screen. Once you have the firefly in your inventory head back to your settlement (Ravensthorpe) and go to the pond with the waterfall which is located to the right of the Seer's hut. If you now walk at the edge of the pond a green prompt will appaer on screen that says ' Release Firefly'. If you now hold the Triangle (PlayStation) or Y (Xbox) button on your controller you will unlock the Twinkle Twinkle trophy/achievement.