I'm not a fan of an accent wall, and especially not in such a small space where it will really chop things up. The grey-blue sample you put on the wall is beautiful. Would you consider painting the entire room that color? It would look handsome with the wood trim. I'd get a white shower curtain with a coordinating deep blue stitch. It will bring a light panel of white to the blue room.

Otherwise, I'd first find a shower curtain you love and then a coordinating paint.

You've done a great job with the new faucet.

I too, love the idea to go blue on all of the walls. I like the idea to do wallpaper too…

I wouldn’t paint the vanity. I’d keep the wood and change the hardware or get a completely new vanity.

Definitely white shower curtain.

And new mirror for sure!

My choice would be Painting all the wood light in the space for such a small bath and only a small source of natural light.

the floor you've selected add warmth, but why not a fun tile?

a frameless mirror.

The dark colors you have sampled will make it seem like a cave at night.

I would suggest a bright white, clean fresh make over with a pretty floor tile

Wallpaper suggestions

https://www.luluandgeorgia.com/products/vintage-floral-wallpaper-by-rylee-cru

https://www.grahambrown.com/us/product/laura-ashley-sweet-alyssum-pale-seaspray-blue-wallpaper/121078-master/

https://www.perigold.com/decor/pdp/the-house-of-scalamandre-ett-hem-anton-33-l-x-2086-w-wallpaper-roll-p002134357.html

https://sandbergwallpaper.com/gustav-light-blue

Mirrors

https://a.co/d/eWOiCdz

https://www.perigold.com/decor/pdp/cooper-classics-toulouse-wall-mirror-p100227800.html

https://moonmirror.co/products/antique-hand-forged-metal-framed-rectangle-mirrors

This is how the floor will appear. I'm not sure this was the best choice.

If you go with a light vinyl floor IMO this pine version is a better fit with your room.