I would not put anything on the house there. It looks like you have vents at ground level. If so you want to keep that area open. Don't plant up at the foundation. All types of rodents love to hide in plantings.

I would build a pretty island bed with a pretty ornamental tree off center as the feature.

Hadn’t thought about the vents .... still would like something on the wall ( where a window would be if it were possible). A bed away from the foundation sounds good, thanks!

Would some kind of metal art work?

You say it’s a cottage. Is it on water? If so, I’d hang old boat oars horizontally, maybe an old life preserver too.

That is maybe a bit too “theme“ like for me but it gets me thinking of other found objects. Thank you!

At least one window and possibly two.

If you can’t add a window, maybe add trim, closed shutters and hardware to give the appearance that there is a 2nd window on the wall. Add correctly sized shutters to the existing window.
I’d be happy solving it with landscaping as suggested by houssaon.

Similar idea to this

A semi-dwarf tree will not get much taller than your cottage. Plant it in the center of the yard aligned with the peak. If you live in a fall colors area, look for a semi-dwarf oak or map tree.
You can plant several flowering perennial shrubs or different annuals every year nearer the house but not in front of the vents, and maybe a bed of low plants around the tree.

I created a "constellation" in a corner wall above the garden with antique/old metal farm artifacts, gears and such. Sourced at antiques stores, re-use markets, and flea markets.

A small ornamental tree. Small crabapple tree or small hydrangea tree planted in the middle.

My first thought would be to put up some kind of trellis or lattice and plant clematis, which I love. Not sure what zone you are in for plantings but in front of that wall you could put a lilac or magnolia.

Or, since you actually wanted ideas other than landscaping, another thought that came to mind was mosaics or stained glass. If you look on Pinterest you will find thousands of ideas for projects you can even make yourself if you are so inclined. Broken pottery mosaics (also called picassiette) are very popular right now (and someday I am really going to make one, LOL!).

If you do a small tree I recommend "Red Jewel" Crabapple. I don't know where the cottage is but I live in Minnesota and planted two many years ago. They are still a manageable size and a nice shape all these years later. The small fruit (maybe 1/2 inch size) stay red and on the tree almost all winter until the robins eat them in very early spring. Red fruit looks wonderful in the snow, then bright pink blooms in the spring. I planted a different variety also and even though the garden supply store said it would be 15 feet it is now at about 45 feet and totally taking over the yard (Harvest Gold). Beware!

I think a trellis would look gorgeous and add instant "architectural" detail for very little cost.

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https://tinyurl.com/yxuhealt

plant a small decorative tree.

I think an arbor would be great with a bed with plantings. The plantings could then by further away from the house

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A few additional ideas.

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An espalier would be lovely there:

Either install a real window which matches the other window, or plant a semi-dwarf flowering tree centered on the empty part of the wall but placed a good ten to fifteen feet from the wall to allow for future growth. A free-form island around the tree could be a nice spot for some low-growing flowers or bulbs.

This would be the least expensive idea you could do. Get some white exterior paint for siding that matches your railing color. Paint the siding strips going from the right side edge of the single window all the way to the right side edge of the house. Paint a single width of siding from the top right hand side of the window across. Then another single strip at the middle right side of the window and across then a third stripe across starting at the bottom right hand corner of the window. Your leaving space between the stripes showing your original house color. So you have 3 stripes no taller or lower than the window spaced evenly out going across the bare wall. This repeats the railing design onto your house and looks like it's planned into the design and will make it look like a window isn't missing on the other side.

I put a wide white lattice on the wall and train something pretty up it- a climbing rose, etc. I think it would be pretty even in the winter and would be above the vents.