

You should check how much of inputs in Vietnam comes from China (while yes, the majority of the outputs goes to the USA), and how much of their manufacturing force have Chinese companies at the core and Chinese supply lines. Also, how much they rely on China for required infrastructure, including how much electricity is currently supplied from Nanning.
Vietnam has potential, but that potential can only be capitalized if it aims to grow alongside a prosperous China.
The Philippines will need some type of revolution, drastically upgraded infrastructure, drastically improved education for its people. Their political structure is basically unchanged for centuries, with a couple of dynastic ruling families and as yet, a population unready for the structured existence of industrialization and manufacturing.
I agree that the world isn’t going to rise up in a united front with China against the US. China (and certainly the CPC) doesn’t expect that, although they do what they can to engage with the global south simply as part of an unchanging decades long strategy. For the CPC, Trump is short term phenomenon reflecting the same long term trend from USA that they always knew they will have to deal with at some point. Although they were probably hoping they wouldn’t have to deal with it quite so quickly.
The rhetoric in the West is really different from the news and analysis in Chinese. It’s calmer and always tend to take the long perspective, small adjustments required but the direction of travel remains steady. Working with neighboring countries is a part of consistent and ongoing relationship-building. While one may leverage the current volatility to get some stuff done, China does not expect miracles. Its confidence comes from know it has the ability to weather these external fluctuations within itself, and when push comes to shove, it can never and will not rely on any other entity.