This is super helpful! Thank you very much. Came from reddit, this is exactly what I needed!
On another note, do you know how to create a texture with the BGRA32 format? I can't seem to get one working in Unity, and converting it doesn't seem to be much use either. The progress bar is extremely useful though!
For whatever reason you can't set a texture to import as BGRA, but you can create a new texture in BGRA format and carry over the pixels to it, like so (also seen in test project on git):
Texture2D ConvertTexture(Texture2D texture, TextureFormat format) {
var tex = new Texture2D(texture.width, texture.height, format, false);
tex.SetPixels32(texture.GetPixels32());
return tex;
}