Reddit mentions of Poundex Shannon Series Dining Chair in Charcoal Iron Finish European Style, Set of 2

With your wall and table color, you could really do any rug at this point. I would stay away from blues simply because your painting is more in the warm spectrum. A nice tan rug would be great if you like simple, or you could do any number of patterns that bring in the colors of the painting.

For chairs, I would also keep those simple because your tastes might change in a bit. I love the look of white chairs with wooden tables, but it definitely steers the look into a more farmhouse style. It seems like you are going for more of a vineyard style, so rod-iron chairs might be cool -- something like this

For the sideboard, I think black might be a good choice -- similar to what is under the picture of the painting. I would pick chairs first, then the sideboard or cart, then the rug.