How to select the last active row and column for a pivot table

If you only want to select column A while in A1
use keycombo SHIFT (hold) + End (just press) + Arrow Down (just press)

if you want to select multiple columns while in A1 (or other start point

CTRL (hold) + SHIFT (hold) + END (just press)

In some cases Select all with CTRL + A will work too