Photography

My partner works in an industry where part of her job is taking wildlife photos for customers, 1-2K shots per trip get curated down to 100-200 and sold to the customer for a small fee, sometimes free. She has rights to the photos and She has every one of the curated photos she's taken over the last 6+ years on a hard drive.

All 209,000 of them.

I realize this is going to be a pain in the ass but I'm wondering what system there would be for ranking them to make them easier to find the good stuff later on. Like being able to rank 1-5 stars and searching later on for only 5 star photos, whatever. (This is a feature in windows metadata, but it seems clunky as I currently know how to change it, open to suggestions)

She wont have to go though all of them and can do some grouping based on thumbnails.

Wondering if anyone has a creative solutions