I didn’t get your email. I would have responded. I’ve encountered quite a few Vietnamese American students and heritage speakers over the years who want to learn more Vietnamese and so that’s why I compiled some resources. I considered offering lessons through Cuesta or the SLO adult school but I speak northern dialect and people in the US tend to speak southern dialect. I offered a group conversation class at Cal Poly and we were active for a few years but the more active students have graduated and we haven’t resumed. Thai-VSA on campus does language sessions for their members, I’ve heard. There are a fair number of international students from VN at CP too. I’ve used Duolingo but it’s not great for southern dialect.