May I ask your motivation for avoiding Chinese PCB fabrication? Considering that 99% of the parts placed on the board will be Chinese, possibly using a fabrication process using Chinese made machines and Chinese raw materials, are your concerns to do with intellectual property, or production and quality control? If you want Chinese prices, cut out the western middle men and pay Chinese factories direct. Just because South Korea is in south east Asia, it does not mean Koreans should be paying themselves at Chinese, or even Cambodian wage levels.
There is certainly nothing more productive than being able to pick up a phone and speak to a knowledgeable human at the sub-contractor, who speaks the same language and is in the same timezone. But this situation has not existed since the 1990s when the G7 'club' dashed towards globalisation, and China reciprocated by exporting their unemployment.
I note my 'Korean' Samsung and LG kit all says on the back
Made In China. Which is the same origin as my Apple and Asus kit. btw, South Korea is renowned for its high volume ship production, which is only possible by outsourcing component(block) production to mainland China. So unless you visit the SK fab house and watch your boards passing through the tanks, is there any guarantee that your product will remain south side of the DMZ?
btw Vietnam is an emerging market.
https://www.mokotechnology.com/top-10-pcb-suppliers-in-vietnam-2022/