Have you tried the chairs with the arms under the table? In my experience, chairs with arms are a pain at so many tables as they bang into the table and don't allow you to scoot up well. The chair you pictured is very attractive though, and the arms look low, so maybe it's not a problem. Just thought I'd mention it.

won't reaching into the cabinets be an issue with 12 inches in front of the doors, especially the lower half, you'd bonk your head and it would create shadows below. also, it seems a bit high to be workspace from the kitchen. I would have wrapped lowers beneath the opening, and incorporated the lowers into the lower half of the pantry while keeping the top as a cabinet. Or open that into a doorway, and add a floating island for more counter space.

Why do you need 40" Get a prefab 36" and there is still 11" of overhang and that is sufficient. That is exactly what I had in my last home and never had any issues and my husband was 6'3. If you are unsure get a piece of cardboard or other flat material and place it on your current bar and sit on a stool and see how it works for you. Wider is nice if you can afford custom, but most people I know are more pre-fab budget people and they are perfectly okay with their counter seating with a 36" wide counter.

I think I would try to make it a design feature by using the same material as your present counter top but in a highly contrasting color or design, and then switch out your over head lights to go with the new contrast. Or, use a very different material from the countertop, but make it a bold choice. For instance, frosted tempered glass (and then you could keep your existing overhead lighting) or slate might be interesting. I think I would try to make it a litttle deeper than a typical breakfast bar to get the right balance. But in the end you are also going to need to move the lights and get some fairly skilled professional work to get a result that is seamless and looks “planned“. Is the material of your countertop precious? Getting a new larger countertop might be the cheapest option.