になるのが

becoming …

→ に
phrase Rare #21,003
becoming … Turns “become …” into a noun-like phrase, with が marking it as the subject.
JA: 医者になるのが私の夢です。
EN: Becoming a doctor is my dream.

トムは子どもの頃、獣医になるのが夢だった。

When Tom was a child, he dreamed of becoming a veterinarian.

でも宇宙船が高くつくのは確かだから、お金持ちになるのが第一歩だ。

But spaceships are definitely expensive, so becoming rich is the first step.

俺は誰かになるのがうまかったんだ

I was good at becoming someone else.

— Pompo the Cinephile (2021)

平和になるのが嫌か?

Don't you want peace?

— 荒野の用心棒 (1964)

彼は教師になるのが目標だ。

His goal is to become a teacher.