The cheapest and easiest way to brighten it (assuming you already have decent actual lighting) is with rugs and art. That won't necessarily be a clean look but it'll feel brighter.

Walls are easy to paint. You can paint the kitchen walls and let hubby have his grey elsewhere.

When you start talking about painting cabinets and changing backsplashes, it becomes a more serious thing. I'd want to change the backsplash because it doesn't seem to match. (It might in person.) But would that be enough or would it cascade to everything else?

I'm not a designer, but I have dark cabinets in my kitchen. The previous homeowners chose a light colored floor and boy am I glad! It would have been too dark, as well.

Figure out how many of those upper cabinets you really need . Be willing to remove what is not essential . Take them down and at the same time redo the backsplash as it looks off w counters altho it’s a good looking tile . Then compose something w a new tile and open shelves to regain some easy day to day / dish/ glassware storage . This will lighten up that space right at eye level and new aesthetic at same time. And not very costly . You could paint the island but work on the wall first. Island can be redone completely in favor of drawers / new configuration / w great reward for you . Depends on budget but new counters are an option / but if you redo island to a white look the counter there could be light maple butcher block or white -other. The light wood top adds warmth / and I’d Pick that.