you are hyper focused. it looks great.

Agree the grout is too dark.

I installed stone tiles in that size in my own kitchen and had my tile guy install them tight to one another with no grout. You don't need grout in all cases.

Grout fills the spaces between tiles and creates a monolithic whole of the installation. It's what gives the installation strength and prevents dirt and debris from getting between tiles. Grout also lightens as it dries. It will be fine.

Some how the pyramids in Egypt and hundreds of miles of stacked stone walls in Britain have manged to survive without grout. There are plenty of backsplash tiles now being offered like split face stone that cannot be grouted, so it is a style decision, however, the tile does have to be installed in a running bond pattern to work.

It looks good to me as well. Looks like you are getting mixed opinions.