STEM salaries for undergrads from USA vs. grad degree from USA with international undergrad degree

“He needs to attend an ABET accredited engineering program.”

When someone says “engineering”, I think that some of us hear “software engineering” (where ABET is not needed, and to the best of my knowledge doesn’t exist). Some of us hear “Mechanical or Civil Engineering”.

I am not completely sure whether the answer to OP’s original question will differ between different types of engineering.