Lots of vent hoods use 10” ducts. Look at Ventahood.

And get a filler in that corner so you can open your drawers. You already have one corner that’s virtually unusable. And the range is going to be off center on the littke wall, which is a major issue when it’s a focal point like that.

Who did your design work here? You need someone different, for sure. Stop this and start over with an actual KD.

Might be able to slip a 6" to 10" transition piece into the wall cavity and run a 6" duct through it. Don't know what you're dealing with on the exterior side though. You can find the transition piece on Amazon for around $20.

You need a 3-fan Ventahood (>=42" wide which will be overkill for your application) to use the 10" hole but there are transitions (reducers) at any plumbing supplier.

you found this after you tiled?

thought you were going to take down that window trim? I believe I mentioned this on another post you had. that trim should have been removed and tile taken to the edge of the window. (it still can be done. just redo the tiles around it. it will look so much better)