if you are going with a tile that dark, I would choose a white floor tile to help brighten up the room. No Window for natural light? even an aqua with a lighter, fresher tone in such a small space.

the vanity top looks to have a lot of gray in it... aren't you trying to get away from the gray tone? Can you find one with a gold vein for your matte gold hardware?

large format simple White tile for the floor. calming and less grout lines not to mention great price.

https://www.wayfair.com/home-improvement/pdp/ackland-segment-blanc-24-in-x-24-in-matte-porcelain-floor-and-wall-tile-mvp11870.html

Love this idea- the vanity will have a white top

Creamy matte tile with possible light vein or texture linen look tile will be a great option: Porcelain Tile. I am a big fan of wallpaper too-a nive texture or light pattern will make a huge difference.

I appreciate your comment, do you have any photo ideas of what you mean by creamy matte tile with light vein or texture? Also I never thought of wallpaper. Great idea

I like this bathroom with green tile that brings in other warm and cool tones, gray floors, wood vanity, white marble and gold fixtures.

https://jessicanelsondesign.com/portfolio/hilltop-revival

It looks like they used Ben Moore Healing Aloe paint.

If interested I think this is the actual tile or very close.

https://ziatile.com/products/absinthe-2x6-zellige-tile

Lots of good ideas here to inspire you. Is that real tile on the floor? If so, would you consider going in a vintage direction? You can find plenty of vintage bathroom images that can provide you with inspiration for that type of look.

You might consider a beige hexagon tile for the flooring.