Would a USD collapse cause trouble for Vietnam?  

I think they would be fine. I don't think they are as reliant on USD and the US economy as other countries but I don't know much about world politics or economic standings at this point. Maybe someone else here has more knowledge on Vietnam's economy. 

It is causing issues already but not the kind you would expect. 

You can read about it in more detail here: https://www.rfa.org/english/news/vietnam/dollar-rises-against-dong-10202022012330.html

I have a hard time explaining it in a way that is easy to understand for people that don't follow debt, banking, finances, or world economies. 

The Vietnamese economy is very strong, with a market of nearly 100 millions consumers, and does not depend much of the US one, the trade is essentially done with Asian countries : Thailand/Malaysia/Singapore/China, South Korea and Japan. 

It is a growing economy. It would take a hit but because it is still young, it will not be as impacted as other countries. They do not rely on the US for much so I would imagine the locals are not worried.

It will be effected. The entire world will be. I am just not sure how much it will be effected. It seems that the US is being pushed out by other countries. Macron of France had a meeting with China and is talking about cutting reliance on the USA now. 

From my understanding, no. There would be no severe issue for them directly from the US... However the US having some sort of collapse with their currency could result in other countries being damaged that Vietnam does rely and do tight business with.