I have not much personal experience with Viets, but let's talk
about culture and history.
(not stereotypes etc)
From my reading and little knowledge, I think they are kins of
Chinese people.
Basically they are Yue descendants who went downwards and
expanded down.
They have some relations with Cantonese (Yue also)
But today they are not exactly the same with Cantonese because
they have mixed somewhat with locals such as Tai and Khmer
groups.
But I think they are still relatively related to Chinese people,
and in terms of culture they are quite related as well. For
instance celebrating Lunar New Year, follow Confucianism/ Buddhism,
and even the language use a lot of Chinese loan words. In the past
they even used Chinese characters before changing into romanization
method.
To me Viet culture is still relatively unknown, maybe due to
wars, but in the future as their country recover and build up, I
have a feeling we will see more impact and influence of them. For
instance, they will send out more students, produce more movies and
dramas, have a few strong international brands/ companies, and so
on.
Meat Bao, you are so well-versed !
My interest is in Asian cultures as well, and as above what you
said is very substantiated. Everything is correct.