How to help without offending?

So my friend is currently pregnant with her first baby and all they have so far is a diaper bag and car seat. She posted a link to her registry and after looking at it she has a lot of stuff that isn’t necessary for a newborn and almost nothing that is necessary for a newborn. For example she has littler swimmers, a bunch of toys (more fit for toddlers) and crib rail cushions, she doesn’t have any clothes, diapers, swaddles, burp rags or things you actually use for newborns. The stuff that she does have that’s necessary is crazy expensive for example a $400 crib mattress. I want to help her and make sure she’s prepared as much as possible for the baby but I don’t want to offend her. I plan on buying her things that aren’t on her registry i.e. burp rags, onesies, swaddles and such but I’m worried that if it’s not on the registry other people won’t buy the stuff under the assumption that they already have it. How would you go about this? I don’t want to offend her but I also don’t want her to have to buy a bunch of stuff herself. If it were you would you be offended or appreciate a friend looking out for you?