is this your only prep area?

In such a beautiful space, I wouldn't have any appliances out on the countertop any way.

you could put the outlets in drawers.

As you already are aware, you can do the outlet strips under your upper cabinets, aka Plugmold. However, the things that you keep regularly plugged in, such as coffee maker or toaster, will have the cords dangling in an unsightly way (see pic). The solution is to have the Plugmold, and also have a couple receptacles in the backsplash just at the place or places where you will be plugging in coffeemaker/toaster regularly.

When you install the receptacles in the backsplash, they should be installed low and horizontal, so that they are less obtrusive and are hidden by toaster, coffee maker, paper towel holder etc. A good height for the horizontal receptacles is 4" on center. You don't want them so low that a thick plug can't be plugged in cause it butts up to the counter, and you don't want it too high so that it is obtrusive. Also buy the receptacle frames that are "screwless", and companies like Lutron and Leviton make them in dozens of colors to get close to the color of your backsplash. There used to be a company that would make receptacles to order to match exactly the backsplash, but they've gone out of business.

Are you aware that quartz is not not advised as a backsplash behind a stove? Particularly a gas stove?

https://www.houzz.com/discussions/5539959/miele-gas-range-self-clean-issue-with-dupont-zodiac-quartz-backsplash

https://www.houzz.com/discussions/4383674/how-to-make-backsplash-more-practical

Beyond that, after living in our first apartment which had only one outlet on the wall behind the only counter top--complicated by the fact that only one appliance could be plugged into it without tripping the breaker--receptacles are a thing of beauty AFAIC!

So I am not in the Hide the Electrical Camp. At all. I want to have plenty of them and I want them easily accessible.

There are undercabinet outlet strips you could put under the upper cabinets instead of adding them to the backsplash area. HOWEVER, check with your local building inspectors first before you have the electricians do the wiring. Sometimes they are OK with this solution, and sometimes they are not. Technically, those undercabinet outlets meet code, but often there are old school inspectors out there who will fail your inspection.

If they won't allow this (or pop-up outlets), you could hire a decorative painter who could do a faux painted finish on the outlets that matches the stone. I had a client who wanted this done for her mosaic tile backsplash and it worked amazingly well.

I did a combination of outlet types. Where I keep my coffee makers plugged in there is an outlet in the backsplash. Everywhere else I used under cabinet outlets, which I absolutely love. Couldn’t be happier.

There are clear and mirrored outlet plates.

You can spend lots of money trying to camouflage the presence of receptacles, but they are there to be used, with cords plugged into them. In my kitchen, most countertop appliances that get used regularly are left out, not pulled out and then hidden away again afterwards. That means you don't see most of my low-mounted receptacles and the cords that are plugged into them because they are behind the appliances. I admire clean design, but, ultimately, my kitchen, like that of many people, is a working kitchen, and it's not realistic to try to make it look like it's not in use.

IMO no quartz behind the range so why not some nice tile and you can get matching outlests from Lutrn . IMO the under cabinet ones just leave all the cords exposed . That IMO a lot uglier than the plugs installed in the backspash I agree first function then pretty .. I honestly never notice my plugs they are there for a purpose .

We also have a slab BS - i did undercabinet outlets (on uppers) except for where i knew i would have a coffee pot and the toaster on the counter and I put outlets there (no way could i deal with cords hanging down for those appliances) For the two outlets in the slab i put them low and horizontal so you can’t see them bc of the toaster and coffee pot blocks them - but i am admittedly a nut about not seeing cords/outlets