No app that I know of but most restaurants have koala stations. They’re pretty chill with letting you use their washroom with a baby/toddler. Some stores like ikea have really nice baby rooms with chairs for breastfeeding too.
Found an app called Mamava! You can add your recommended nursing/changing room space but they have their own pods around downtown Toronto!
Is there an app? I would love one and where the clean secure ones are too! If we can't find one, we normally change our LO in our car(one of the seats or the back if you have a van).