@irene I've not seen anything specific, but maybe you could find someone local to set up this: https://codeberg.org/flohmarkt/flohmarkt?

I just set up one for myself (and hopefully locals) to play with near me...

The other thing could be to try lemmy and their forums?
There are some locallish "for sale" communities

https://lemmy.ml/search?q=sell&type=Communities&listingType=All&page=1&sort=TopAll&titleOnly=false

@irene
Slightly sideways answer but just checking whether you've heard of #freecycle?
Looks like the Seattle group is pretty active
https://www.freecycle.org/town/SeattleWA