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
What if you could log in with your Mastodon (or other) Fediverse account, and they would too, so you could see their user history and connections? (And they could see yours)
That would be cool!