Yes, these two cases are closely related https://en.wikipedia.org/wiki/Locative_case#Russian but it is better to distinguish them, because Russian still has some archaic remnants of the original locative.
The English for is extremely overloaded and is used for great many completely different meanings.
The basic meaning of pro is when something is given to someone or meant for someone. I did it for you. Udělal jsem to pro tebe. Tohle je dárek pro tebe. This is a gift for you.
Na has very different basic meanings. Most often a location or direction (on the wall - na stěně, onto the wall - na stěnu). But is also used with many verbs. And it is also used when something is aimed to be used for something: This drug is for flu. Tanhle lék je na chřipku. This is for washing. Tohle je na mytí.
Anyway, in any foreign language you typically need to learn the prepositions belonging to each verbs one by one. I had to learn English phrasal verbs one by one (and still do not remember many of them). There is nothng logical or rule-based here. It is case-by-case.