Hmm I was looking for a solution, but now I am stuck too with this:
https://playground.babylonjs.com/#SA6QBM#1
With .glb files I get "Error: “Unexpected magic: 1852139298”
And with .babylon files I get "SyntaxError: “JSON.parse: unexpected non-whitespace character after JSON data at line 1 column 10 of the JSON data”