Sweden and Finland both have vegan burgers offered by McDonald's due to the growing number of health and animal conscious customers in those countries.  They appear to be a great item there.  Here is some information about this:

https://www.npr.org/sections/thesalt/2018/02/21/587406992/even-the-hamburglar-might-like-mcdonalds-new-mcvegan-burger-we-did

McDonald's should start to carry this in the United States, as even here there are vegetarians and vegans that would always have an option given that a McDonald's restaurant can be found virtually anywhere.

Animals don't have a voice, so we have to be their voice.  If establishments like McDonald's start to offer vegan burgers in the US, it would be an enormous step in the right direction for animal rights.  Further, it would open McDonald's to a great number of customers they rarely (if ever) serve now.  Combined with their fries, this would be a tasty lunch or dinner (note their fries are vegetarian but not vegan).