I have to start by saying that I am not a yarn snob (which probably actually automatically makes me a yarn snob) but I am not an acrylic fan. I don’t like the way it feels in my hands when I’m working with it and is not at all forgiving. You’re never going to “block it out” in acrylic. It’s also highly flammable (it’s a petroleum product) and pills like Courtney Love on a bender.
That said, that are lots of great yarns that are machine washable. I’m a big fan of Cascade’s superwash yarns. Also Neighborhood Fiber Company’s superwash. Yes, I know, it’s a chemical process but it’s the lesser or two evils and it maintains the blockability, breathability, and sturdiness of 100% wool. I like to identify as an environmentalist and try to avoid things like plastic but that family sized Green Apple Suave Shampoo in my shower right now is in a plastic bottle so I try to keep my hypocrisy in check.
Any superwash that I use goes in the washing machine and then in the dryer (dramatic gasp) just to “take the wet out” of it. Usually takes about five minutes so it’s just damp and then I lay it flat (sometimes with some pins) until it’s fully dry. Superwash might pill a little but, generally, it only pills once. Shave them off with a cheapo razor and Bob’s yer uncle.
As to patterns, I’m a huge fan of the Korrigan set from Solenn Couix-Loarer. Here’s a Ravelry link to her pattern page. There’s a hat, a blanket, and a tiny sweater. It’s 90% easy as pie and then a little tiny challenge on the cables. Not a hard one, you just have to pay attention. I’ve made the blanket at least a dozen times.
If the wee bairn is in a warm climate (or not), you can also try Kay’s Stripey Baby Blanket. I made one and it is easy, fast, and I want one for myself. It’s generously sized, beautiful, and ridiculously cozy. Did I mention that I want one for myself. You can pair it with really any other sweater, hat, and/or booties.
It’s wonderful of you to make this for your friend. All babies should be welcomed to the world and immediately handed a present that is full of love. They’re brand new and are not yet subject to the idea of deserving to be loved. It’s simply handed to them - no questions asked - when they arrive and a wonderful way to begin a life.