Sounds like the baby knows exactly what he needs. It is very shocking to have your first baby - and then discover that little bundle of joy is "high needs". That's exactly what happened to me.
My son was the epitome of "high needs". Just like the baby you describe, he had to be held 24/7 or he screamed constantly. When he was in arms, he was happy. My son slept on my chest for 6 weeks, because that was the only place he was happy. And when baby is happy, the whole family is happy.
It was pointed out to me, by some very wise mothers, that babies - especially newborns - know exactly what they need and they will tell you. They don't have any agendas. Just like you, they feel scared, intimidated, unsure and overwhelmed, etc. They don't have the tools to deal with those things yet. The only thing they know is the warmth and comfort of mama's smell and the steady thump of her heart.
We had a pretty traumatic birth and post birth experience, so that very well could have been the root of my son's "high needs" issues.
Tell your friend to go buy a comfortable sling and wear her baby. It's the most natural thing in the world and best for baby. There is a school of thinking called NINO, Nine In Nine Out. Meaning the healthiest thing for brain development is nine months in the mama, nine months ON the mama.