If you'd prefer hard copies of these watercolors, there's a recent apple "opus" that came out that includes 1400 of them: https://www.jakkawpress.com/. It's a six volume set, currently marked down to $150. I'm tempted.
"The lavishly illustrated hardcover set of seven volumes (each 500-600 pages, 8½” x 11”) comprehensively documents all apple varieties that have appeared in publications in the United States and Canada through the year 2000."
16000 varieties. And only through the year 2000. I'm stunned at the diversity of the apple.
Not to detract from your wonder, but apples aren't true-to-seed... so each new seedling could potentially produce a named variety (although most end up trash trees either with undesirable fruit or susceptible to disease).
Oooh, me too. I have no idea why this is so appealing.