This is out of idea with the M35 helmet (The most iconic german helmet during World war 2)
''texture of helmet is in the shoe texture''
Now I know how to export character with facial expression
(no unity require)
it's easy 1.open your blender
2.editing your epic character
3.if you finish your editing
character, Then select everything
4.go in editing mode
5.click mesh(on the top left) and
find the Triangle face and click
6.export as VRM