I recommend changing the title of this forum to Cesium for Godot as the new repository started by @brynn_b comes with close to almost full coverage of API provided by the latest version of Cesium Native but repurposed for Godot.
The organization behind the 3D Tiles for Godot project, which presented at Godot Con Boston 2025,has recently acquired for supporting military purpose.
Please read more here
The new initiative support both GDScript and C# (like Unity for Cesium)