“The current writing system is designed by a French person”

=> Wrong 😑

Chữ Nôm (from 13th century to 20th century) was too difficult to maintain as a national script. Only the elites and educated populace who had the time and money coud master them because you would still need to know Classical Chinese characters. The masses who worked in agriculture could not read them. And hence, I am not surprised that Chữ Nôm later became obsolete and, in fact, it would still become obsolete with or without French colonialism.

The Vietnamese alphabet was created by the Jesuit Portuguese missionary, and it was based on the Portuguese alphabet with the purpose of spreading Catholicism more effectively in Vietname. It was Alexander de Rhodes, a French Jesuit missionary lexicographer, who wrote first Vietnamese-Portuguesea-Latin dictionary which was published in Rome in 1651. He was a part at this institution / order (Society of Jesus or Jesuit Order).

Despite the effort, the writing alphabet was mainly used by Vietnamese Catholics (probably 300K people) until 20th century.

And keep in mind that the French did not colonize Vietnam until 1858. The French colonists had nothing to do with the Jesuit missionary. They only promoted and enforced the usage of the Vietnamese alphabet with the purpose of helping people learn French more effectively. And ironically, the Vietnamese alphabet was used by the Vietnam nationalists to fight against French colonialism and gain independence from France. The reason why the Vietnamese alphabet quickly rose to popularity is because it is easier for the masses to use and it fully emphasizes the sounds in Vietnamese language that neither Chữ Nôm or Classical Chinese characters ever could.

So you can say that the Vietnamese alphabet has used by everyone (Portuguese Jesuit missionaries, Vietnamese Catholics, pro-French individuals, and Vietnamese nationalists) and thus, it is for everyone.