Is the first pic your existing kitchen? I'd be hesitant to go green with the maroon flecks in the granite, but it depends on the actual slab and how the counter "reads" overall. If it's more grey-white with a little bit of maroon they green could look great, but if the maroon is prominent then no, go with the white.

It’s AI mockup of kitchen reno. Floors, cabinets and granite selected. Roll of dice with slab.

I suppose open to different countertop with green tile too. I prefer natural stone.

Backsplash should come later, after the cabs and countertop are installed in your home. Focus on getting teh cabinets and countertop right.

"roll of dice with slab"

Bad idea. You should pick out your own slab(s). Exception would be for a very small job where you really don't care much and the material tends to be more uniform.

I’m coordinating the reno of my mom’s kitchen from another state. Only option.

They are going to give you the ugly slab at the back of the warehouse, that no one would buy in person. Someone needs to pick this out ...

a safe bet if you are coordinating off site, is to go with the first choice of subway tile. its a small kitchen and the countertop slab is somewhat busy so id pick out a neutral color backsplash

^^ Good advice from Diana. White cabs with black or charcoal grey counterops are a classic.

A good charcoal grey is Steel Grey. I especially like it in a leathered finish, though leathering will lighten it. Virginia Mist (Jet Mist) granite is a stunning black stone with white flecks/swirls though it -- one of my favorite stones.

Here's a picture of Virginia Mist (not my kitchen):

Curious designers opinion regarding comment “it’s a small kitchen and the countertop slab is somewhat busy”.
Our designer said the tile bs with grout can also come across as busy.

Grouted tile is busy if there's too much contrast--say white tile with dark gray or black grout. White tile with white grout is much more subtle, as is dark tile with dark grout. So it depends.