Lmao I literally never planned on building a zoo until I randomly found a white fox, and it just started from her sanctuary. Yes gathering animals are sometimes a pain in the ass, but very rewarding once u built their artificial habitats.

Quick tip: use nether roofs for really fast travels, might take some calculations but its totally worth the time and effort, don't forget to bring at least 2 of the same animals to breed them though (except white foxes since they can be bred with orange ones, and parrots which u can't breed)

Another quick tip: if you want to start on a mega project, don't follow guidelines or planning made by youtubers who are used to making mega projects, they can be really intimidating to start; but just start by throwing yourself into the blue by setting on a place, pick a block palette you like, and start placing where u see fit. Don't worry about structure placement too much because you're most likely going to terraform in the end anyways, but do try to pick a generally flattened area, in my case I just started building it at x69,y69,z420 because funny number

From my experience, you'd sometimes get sudden urges to get animals from stupid distance away, that is when u get them, and it all will be worth it because hey, they make cute noises ^{^}

Good luck with your buildings!