Its been out of production since at least 2014 (the age of my own
eper) so its very unlikely you are going to find one in a traditional parts shop/supplier - it will have to be new old stock thats been on a shelf for a long long time. Sure one will exist out there somewhere but i think my starting point would be local owners clubs and facebook groups for people that might have a stash or are breaking cars.
I would call it the oil breather pipe if i had to give it a name.
failing that you'd just have to make something out of pipes that fits, hassle but its not the most complicated item, could do it with a t-piece and 3 bits of pipe and some pipe clamps if needs be, wouldnt be pretty but its mostly out of sight.