Anyone here actually talking from real experience of actually having kept the two fishes together for some time, or merely speculating as to what they would think would/should happen??
Angelfish are very deep bodied, even at a very young age. Their desighn is to prevent being easily swallowed. Back in the 70's, when I was a kid, a young angelfish was one of the very few fish I could buy from a pet shop that could be added directly to my CA/SA tank with out having to be grown up ( so it wouldn't get swallowed). Angelfish were seldom bothered and usually left alone. Had a very large and impressive angelfish for almost 5 years with large oscars in a 4 ft. 100 gal. ---- but also RD. One day the Red Devil bit the angelfish and totally destroyed it's head in one little bite. But of course that's aggressive CA
Had angelfish with oscars a few times since ------ even had oscars lay eggs and totally ignore a group of angelfish that always hovered above them in a 6' X 2' x2' tank!!!!!
My experience keeping oscars with angels is that the oscars ignore them; leave them alone. I know of others with very similar experiences. But of course it's high risk , as one bite from a mature oscar, though nothing really like an RD bite, could severely injure or even kill a fragile angelfish.
If you try it, I would suggest having a large enough tank ( 150 gal or more), and have other tankmates as well to pre-occupy the oscars. No gaurantee that it will work, as is the case in any cichlid tank, as there are always many variables involved.