They’re a fast-food joint that sells coffee, or anything else that they think is a hot seller (they also sell smoothies now, iirc). They’ve always tried to latch on to the latest hot trend, and often the detritous lingers on the menu after it passes - they didn’t always have all those chicken sandwiches, tenders, and nuggets, but KFC and Popeyes were hot for a minute and off they went. I also recall a brief flirtation with pizza and tacos/burritos.
A McPizza and a McTaco/McBurrito? Sounds intriguing to say the least.
Here’s a listof failed attempts at menu expansion - pizza’s included. But Googling it, it looks like McDonalds briefly sold Taco Bell tacos/burritos in some areas, rather than had their own. Weird, but I never ordered one so I wouldn’t have noticed; I just recall seeing them on the menu.