How to learn nothern Vietnamese?

Hey I'm a german middle eastern girl and I really want to learn vietnamese in order to better communicate with my boyfriends mother. He is from Hanoi and I really want to learn vietnamese with the nothern accent but all apps seem to be in the southern accent, which is way different than what he speaks. I already learned a lot about his culture, and we often find a lot of similarities. He is very interested in mine and I want to show him how important he is to me as well! Thank you all🌸

EDIT: I seemed to have open a big discussion 😭 I said/made this post because whenever I learn with my boyfriend, or try to practice myself I send him the things, thats when he tells me that they don't say it that way/ use different words or that the pronounciation is more southerly than northern. I don't ever want to offend anyone. I just want to be able to communicate with his mom!💗 thanks for the great advice!

Edit 2: we broke up. Thank you all for your advice I will be leaving this post up incase any of you need tips.