AVR Pointer Atomicity
Why are you worried about pointers in particular? They are really just variables like any other.

The key issue with concurrency, such as between non-interrupt code and interrupt code, is when you have two concurrent threads that access, or more importantly, modify the same variable (whether it is a pointer or not). It is those shared variables that you need to consider protecting, especially if the operations on them are not intrinsically atomic.

Operations on non-shared variables (or pointers, or structures) do not need any special treatment.

If you do share a pointer between concurrent threads, keep in mind that any data that the pointer points to also needs to be considered "shared data" and needs to be given the same considerations.