Interacting with 3D Graphics, for export

First let's take a 3D element:

g = PolyhedronData["Spikey"];

• Export as GIF:

  As stated here one can Export a List of images as a GIF:

  animation = Table[Show[g, Boxed -> False, 
    ViewVector -> {0, 5 Cos@u, 5 Sin@u}], {u, 0, Pi, Pi/20}];
  Export["~/animated.gif", animation, "DisplayDurations" -> .1]
  

  giving:

  

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But since the question is "Are there any export formats which preserve the ability to interact with 3D Graphics? (In particular, the ability to rotate.)" I propose the following which I find very interesting:

• Export as STL:

  Export["~/Spikey.stl", g];
  

Then one can use Sketchfab to visualize it and get the ability to easily interact with it (click for the full ~3MB GIF):

• Spikey

• Sin[x+y^2]