Viet dynasties took Confucianism-Sinification too seriously was why they didn't last long btw. Trần dynasty started going downhill when Emperor Anh Tông fled when his father tried to tattoo him so he wouldn't forget their Yue bravery martial roots.
China only truly forced Sino culture on Vietnam during the brief 20y Ming occupation, which was reversed. The Lý-Trần eras were still largely Baiyue.
Confucianism was adopted voluntarily top down by Viet dynasties (Lê), or gradually influenced through peaceful migrant.