>>”reproductive fitness” is if not a form of eugenics?
Reproductive fitness is merely the measurement of a genome’s ability to produce viable offspring. Typically measured over multiple generations.
It could apply to plants as well as animals.
Maybe in your Parrot’s Newspeak Dictionary, Gregor Mendel was a “Eugenicist” when he was measuring viability of (genetic) traits among Pea plants.... but in the real world, he was just a horticultural scientist (and an Augustinian priest) trying to figure out why some plants produced better/more fruit than others.
In other, more modern, words he was measuring Reproductive Fitness of Peas.
When it comes to Mendel you are playing real fast and loose with the facts. Nothing you said matches with anything about his history or his contributions.