NO GRAY it is beyond current

Go to an actual tile store. No box stores. No seconds like F&D.

Anything that we would show you online would not do it justice. Tile needs to be seen in person for best results.

Here's a sample of what we've done

I want to keep it light in my bathroom as there is no window. What colors would you put with the light grey to keep it that way?

Keeping it "light" in a bath involves upgrading your lighitng. Even an all black bathroom can be bright and welcoming, with the right lighting. Pick whatever colors you like! Then add the right lighting. What is your favorite color?

^^^The lighting you install will make all the difference. I have a guest bathroom that doesn't have a window - but after adding additional lighting, I really don't think about it being "windowless" anymore. I actually almost added a solar tube or skylight - I'm glad that I didn't. While I do love natural light over artificial, putting a hole through my roof in order to add natural light to this bathroom wasn't really needed.

I installed charcoal slate tile from Brazil on the floor (4x12 in a herringbone pattern) + white vanity with a real Carrara marble countertop + Zellige style tile in the shower.

All gray can be ok but, for me, it depends if the gray is warm or cool toned.

I have worked in a prison, and -- yes -- every last thing is gray. I'd suggest you lean into white or cream instead, especially as you say you have no natural light in your bathroom. All white or cream will be more "crisp and clean", and it'll allow you to change to any color accessories you wish over the years.

Love the blue tile in that Minardi's inspiration picture above, but I don't care for the large gray hex tiles outside it. Can't say WHY they feel wrong, but they do.