Looks fantastic - truly inspiring
I've used that special walnut atain before too - good stuff.
I've heard of using shellac as a pre-stain sealer but not filler. I'm trying to use lacquer like you used shellac as a grain filler, but it's taking forever. I think maybe each coat of lacquer is "melting" the previous layer and causing it to raise up again. Does the shellac work well as a filler? It sure looks good.
P.S. Are those robots on your wall ?