As this project appears to be fairly unknown in the fediverse still, I’d like to use this opportunity to advertise Flohmarkt. This Fediverse equivalent of Facebook Marketplace already has some instances up and running - see here: https://codeberg.org/flohmarkt/flohmarkt/wiki/flohmarkt-instances
But telling a friend about this starts with the name. Simple names are easier. And that would just start with making it short. Single syllable being best.
Like eBay, Facebook, Twitter, Amazon?