I was over at a friend's house and had the chance to handle his new Canon R5 with 100-500. The eye tracking on his moving dog was impressive. Ergonomics were good also. He likes the files he gets for his landscape photography. Of course the R5 would be beyond your 2k budget. I would look at a mirrorless with good eye recognition and tracking for her use with wildlife, birds, humans, and pets.
DP Review liked the Nikon Z5 as an entry-level fx mirrorless. https://www.dpreview.com/opinion/35...st-made-the-best-entry-level-full-framer

If she wants to stay with a dslr, a used Nikon D850 would be the best way, imo.