Thanks for the detailed floor plan! That is very helpful.

Since it is gridded off into 1 foot units, I counted the squares where you could put an island in picture #2. You have 10 squares across, and 9 down, so 10' x 9'. I did not go into the lower nook.

You need space to get around the island. An absolute minimum of 3 feet, which would have you hating the island and thinking it is too big. 4 feet is better. You need that on the top and bottom and on the right side. You don't need it on the left, since that is open to the foyer.

Take 4 feet off the top and bottom (i feet total) and you have 2 feet left. Take 4 feet off the end and you have 5 feet left.

Would a 2' x 5" island be functional for you? It would not be for me.

I would not raise the window, unless it was absolutely necessary. It looks like you have enough cabinets.