Hi, You can get the entire kitchen installed before deciding on the backsplash and lighting fixtures. It's best to see things in your space before deciding. Get cabinets and counter in place then post pics of your kitchen.

Unfortunately it’s a new build where we have to make our selections prior- the floor we picked was Mohawks sand dune collection, wall color: repose gray

I think with the stone Grey island you won’t need the grey backsplash - and the fact that you are doing grey walls leads me to say ‘backsplash that matches cabinets exactly!’ Make sure your builder has a countertop fabricator that knows patterned quartz seaming and make sure you are looking at current white cabinet color under correct lighting (old discolored cabinet sample and / or wrong lighting could lead you to select a white that is off. Matching cabinet color exactly is your goal).

Do they have a design team? This problem of builders forcing homeowners to make all their decisions came up recently. It was suggested to the OP to ask the design person since lots of other people probably picked the same combination. From the above comment, I agree the backsplash being close to the color of the cabinets gives you the opportunity to change your wall color in a few years if you tire of the grey. It looks like it’s going to be quite classic and lovely.

I love the gray backsplash... looks really nice!