I live in the Midwest so I know the ones I buy have traveled a long way and probably have lost some of the flavor. I have found frozen mangoes but they of course aren’t as good. I had no idea there were so many kinds.
In the worst case, visit a grocery store catering to Indians. They will stock canned mango pulp from Alphonso mangoes. It is not fresh mangoes, and usually has sugar added but taste is good. The mango pulp is quite thick, not runny. I like to pour a teaspoon of melted butter on the pulp in a small bowl.