Using moment or key feature point based initial alignment before robust ICP is a quite common pattern.
@muratmaga would like to get a similar method ported from Open3D to VTK. See some more details here.
You can also have a look at CloudCompare’s mesh registration and if you find methods that work well for you then port those to VTK/Slicer. CloudCompare is GPL, so you cannot use anything from it as is, but it is good for testing an approach before spending time with implementing it (or searching for existing non-restricted implementations).