Is there a way to leave feedback on a seller if the purchase was never received?

I purchased a sweater 10 days ago. It still has not shipped and I can see the seller has been active in her closet every single day. I sent a private message asking if she was planning to ship soon and got no response. I waited a couple of days and then left a comment on the item itself in case something was buggy and she never got the message (I’m not a seller, just a buyer so I don’t know how that works). Anyway, no response from that comment either even though she’s been online. I have yet to cancel the order but think there should be a way to leave feedback so others can see or a way to complain to Poshmark or something. This is actually the second time I have been ghosted by a seemingly active closet and I don’t understand why people do that. If you need a while to ship, no problem but communicate that!