Yay it works!

AnimatedCube.bin

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:82de770fc82b48a77a33bb26abd4d7e75620491b36ddf98e8dca69fa73dd798c
+size 1860

app.py

@@ -9,8 +9,12 @@ cube = GLTF.load("./AnimatedCube/AnimatedCube.gltf")
 
 def load_mesh(im: str, choose: str):
     print(im)
+    # let's first clone the source model
     model = (avocado if choose == "avocado" else cube).clone()
-    res = FileResource(im.name)
+    resource = FileResource(im.name)
+    model.resources.append(resource)
+    # let's do surgery
+    model.model.images[0].uri = im.name
     with tempfile.NamedTemporaryFile(suffix=".glb", delete=False) as file:
         model.export(file.name)
         return file.name

toto.py

@@ -0,0 +1,11 @@
+from gltflib import GLTF, FileResource
+
+gltf = GLTF.load('./AnimatedCube/AnimatedCube.gltf')
+
+model = gltf.clone()
+resource = FileResource("/Users/gibbon/Desktop/hippo.jpg")
+model.resources.append(resource)
+
+model.model.images[0].uri = "/Users/gibbon/Desktop/hippo.jpg"
+
+model.export("toto.glb")