Is “In official history, Xiao Yu was an important minister of the Tang Dynasty, and the novel adds his proposal for Buddhist affairs.” true?

The official history 《旧唐书》 records that Xiao Yu was an important minister in the early Tang Dynasty, stating: "武德五年，迁内史令。时军国草创，方隅未宁，高祖乃委以心腹，凡诸政务，莫不关掌。" (《旧唐书·封伦萧瑀裴矩宇文士及传》) In Chapter 012 of 《西游记》, he appears as the prime minister, petitioning Emperor Taizong to select eminent monks for a grand water and land assembly, thereby setting the stage for Tang Sanzang's pilgrimage to fetch scriptures.