Nike Court Royal is not a rare shoe. Just go to the shop and try.
26.5cm should be US size 8.5 to 9.
I jog regularly and have a wide foot. My true to size is 25.5cm but usually I ended up buying us size 8 coz for jogging and running. In sg weather. Our feet will expand during the long run.
I have both Adidas, New balance, asics and Nike shoes and I feel Nike shoe has the most narrow fit for most of the shoe. For Nike. I need to wear size US 8.5 size. As for other like Adidas. I can wear even wear US 7.5. If u want wide shoe. Look for wide fit cutting like 2E or even 4E shoes. Only new balance and asics are offering it.
I dislike buying much bigger size shoe just to wear it. Another way to wear it comfortably is to remove the insole.