First, Please pass on our support to your nephew, and your family. Can't imagine what you are all going through.
Second, there are some 'therapeutic' style chairs that can help a person in and out of the chair easily.
https://www.phc-online.com/Golden_Da...r_p/pr-632.htm
My grandmother has one like that.
Or, if he just wants a comfy chair, lazyboy is about as good as it gets. Stay away from the brick etc.