VinFast already ditched their entire gasoline lineup. And on semiconductors, even within SEA, Singapore shut down its own fab back in the 2000s, and Malaysia, with far more experience and a deeper industrial base than Vietnam, still hasn't seriously gone down the path of building their own domestic fab.
So I don't see any guarantee Viettel can LEGALLY move past 32nm, given how export controls and tool access actually work. And if you're stuck at 32nm, "competing" is basically a knife fight in a mature-node, commodity-priced market that only makes sense if you don't care at all about profits or running costs.