the point is: its happened before, that means ya shouldnt be surprised that its happened before. to be fair, Zarude looks way different than a normal pokemon, you would hardly see a pitch black, feral looking monkey be available as a non mythical Pokemon
I can understand the point that 2 primates are in the same region, and both can be very unrelated to it, but the 2 pokemon are somewhat considered special pokemon
1. you can't find starters in the galar wilds
2. Zarude is a mythical Pokemon, which also can't be found in the galar wilds
it doesnt really matter if they are totally unrelated imo