It would be useful if there was adopted in the Standard that iterators of two instantiations std::array<T, N1> and std::array<T, N2> had the same types of iterators.. In this case we could use lists of iterators for instantiations of std::array that have the same type of the first template parameter.
If you wish to erase the extent of the array, you can use a dynamic span iterator.
Although it might not be the same type as std::array<T,N1>::iterator or std::array<T,N2>::iterator, there's already an even simpler iterator type which can be used with both arrays, erasing the array extent. That iterator type is of course "T*", as obtained from (data()+k).