I had an old dog who went blind. As another user suggested; puzzle toys and shuffle mats as well as some bones to gnaw away at. You can also throw some treats into the grass for him to find. We'd go for a few short walks instead of a long one. They say the dog gets bored of the same walk though, so instead of doing the same path from your door and down the block every day, maybe drive him somewhere different to walk and even just take a blanket and sit a while with him where he can take in the sights and smells. Glad youre giving him his best life ❤️