1) Buyer messages you, wanting local pickup, but claims they can't pick it up themselves and wants to prepay (but won't pay through Facebook or an eBay or Mercari link if provided). They ask you for your Zelle info. Then they'll tell you your Zelle isn't working and needs you to confirm it with them, you'll get a confirmation code, give it to them, and they'll have your Zelle account.
These scammers' accounts typically look legitimate but are often from other cities/countries with no relation to yours. They will engage you in complex conversation about arranging pickup but typically will disengage and block you if you tell them flatly that you do not accept prepayment via Zelle.
2) On eBay, as a buyer, scammers seem to have access to tracking numbers for nearby but not actually the same place. They'll ship things to you with an apparently legit tracking number, and when it never shows up, blame the shipper.
I have to say that I am not sure how this latter case is making money - eBay nearly always sides with the buyer in these kinds of disputes.