I've picked up a few non-essential items (Easter basket stuff), but it was during a trip to Walmart for essential items.
I see nothing wrong with picking up some non-essentials if it's at a store you are already going to for essential items. Have a rough idea of what you want, don't touch everything, and get in and get out.
I also see no issue with ordering pick up or delivery of any items as it drastically limits contact and helps to keep places in business.
I think it is violating the spirit of the stay at home orders when people go to stores because they're bored/just to get out of the house. I have a relative who goes out to different stores several times a week simply to browse out of boredom. She's one of those people who will go up and down every single aisle in Walmart/Meijer/Target just to see if there are any new sales, grabbing items to inspect them then putting them back, flipping through products to grab the one in the very back, touching everything, etc. From talking to her on the phone, it sounds like her behavior has not changed with the stay at home order in her state. She told me about the 7 stores she went to in the span of 3 days just to see what was new/check out the kids clothes, etc but she didn't find anything she wanted. For perspective, this woman is my mother so she has no "kids" to buy clothes for. She has *never* bought clothes for my nephews and we live in a different state now so it would be impractical to buy anything for my kids (they don't need anything anyway, and if they did, I'd get it myself so I could ensure its something they'd like and would fit). There was zero need to look at/buy kids clothes, and she admitted she didn't need groceries or anything else when she went out. I've been telling her to stay home, but she won't listen.
It's things like that which drive me nuts.