In the same way, any naively "constant space" algorithm that indexes into an array with a fixed number of pointers or indices is technically O(log n) in space,

In the same way, any naively "constant space" algorithm that indexes into an array with a fixed number of pointers or indices is technically O(log n) in space, since you need log n bits to index n objects. So a space factor of log n can generally be treated as constant in practice.