PowerPhotos for Mac has archived my full “keep originals" 1.4tb photos for Mac library to both an external SSD + up to my NAS for safe keeping. I am now moving 1.4tb sorted b year JPEGs folder (exported using PowerPhotos) to my NAS for then eventual upload to Amazon Photos.

My Lightroom Library for 4 terabytes is 75% uploaded to Amazon Prime photos then I'll start uploading the photos JPEGs copy.

It's a long process.