Read this article in Veg News about a Burger King in Spain that is offering an entirely meatless menu. I am adding the Veg News link because I could find nothing on the Burger King website about this: https://vegnews.com/2021/10/burger-king-in-spain-meatless?fbclid=IwAR3w8_4DRskakRA7gcb6hy2qWiIODYOclSVJ7xt4lqv3sCSVEsyYLOYK7_I
Veg News is a great resource if you are interested in a vegetarian or vegan lifestyle.
One thing to remember is a restaurant may use plant based meat alternatives but might have mayo or sauce that is not vegan. Of course, you can always ask to leave out the sauce if desired.
The second thing to consider is this is still fast food, heavily processed. It may be “better” by some measures, but it is still worth trying to avoid or reduce the processed foods in your life.