Something natural and organic--like woven shades, in matchstick, bamboo, grass, etc. Adds texture but is neutral.

Can you post a picture of the blue island?

I'll be in the minority here since most Houzz pros seem to simply loathe vertical blinds.

I, too, have a side/slide kitchen window about that same size (width and height) and last summer as I repainted the kitchen made the mistake of changing out light blue vinyl vertical blinds (that date back to 2017) for the new white mini blinds (with out the strings) to change the color. :-(.

The vertical blinds were by far more practical and not just because the window is a side slide window but because the kitchen window has a western exposure and the vertical blinds were far better for light control options -- and were much easier to clean.

Suggest white vinyl vertical blinds; however, one caveat: that light might be too close to the outside wall for them.

Do you need to add window treatment for privacy? for light control? for decoration?

If you only seek decoration, then consider just adding a long swag -- one that covers the wall over the window and the window trim above and on both sides of the window but very little of the glass.

https://windowtoppers.com/collections/kitchen-curtains-and-valances/products/roslyn-3-piece-tailored-country-swags-filler-valance-window-curtains-set-with-banded-edge?variant=46144210566

Not for privacy or light control. The window looks out over a second floor deck. It's mostly because of the cold weather in the winter, and for decoration...I feel the cold coming in, even though windows are new and double paned. It's a plain area but has a nice view.

view.

I like the idea of a natural woven shade. Maybe it can have a cloth backing to keep out the cold? Color ideas? I'm not good at this, at all. I lean towards jewel tones in my decor. I'm wowed by the advice I've already received, and so thankful. I need to use Houzz more often.

Might I suggest you add a solid glass storm window rather than hoping the window treatment would block the cold?

Would not want a glob of bunched up shade on a kitchen window to collect mist from fried foods -- but to each their own. An old fashion roll up shade would be better for the kitchen.

Consider another way of weatherizing your window during winter until you can add a storm window or change out the window itself for a window rated for cold.

If you choose the swag to hide the tacks or staples, you might be able to keep the natural light while blocking the cold using a plastic sheeting method to create a "dead air" space between the window glass and clear plastic.

There are kits available at the big box stores that you can use to put plastic over your window and then apply heat with a hair dryer to tighten the plastic so it mostly visually disappears (unless you're looking for it or see how it is attached to the window.

https://www.google.com/search?q=plastic+over+kitchen+window+for+cold+climates&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiE8Kj7h5HmAhVkS98KHcknArsQ_AUoAnoECA0QBA&biw=1328&bih=617#spf=1575086909808