Disabled Removing Shoes

My friend is travelling to Japan in December. He has a disability that requires him to wear leg/foot braces that require wearing shoes and that are difficult to put on and take off. Once he takes them off walking is a real trial for him with the possibility of falling. Is there any way to get around not wearing shoes indoors? He could jury-rig a pair of indoor slippers to work with the braces when he arrives at a place where you're supposed to take your shoes off--would that be OK?

Unless your friend is going to visit someone's home, go inside temples, minshuku or traditional Japanese style ryokans, there are not many places one has to take off one's shoes.

If he plans to visit such a place, maybe you an talk to the people of the place in advance and see if it is OK, for example, to cover the shoes with thick plastic bags or use huse slippers or something to put over the shoes instead of taking them off.

Wearing shoes inside ordinary home is a big no-no because shoes could damage the flooring (especially tatami) and/or bring in soil and dirt inside where people walk without shoes.
If he needs to go inside such a place, the best solution is to prepare something to prevent his shoes would damage or dirt the floors and make explanation well in advance so there won't be problems on either side.

If he is careful to pick up a place to eat or stay, it is not difficult to avoid taking-off-shoes occasions.

Wish him a nice and enjoyable trip in Japan.

Perhaps you can visit Home Depot and pick up some shoe covers for painting in the event they do accept those covers over the shoes as enough to be able to walk on the delicate surfaces....