You can also post something to the marketplace directly in #Amethyst. It will show up in Shopstr, too, as they use the same event kinds for their listings.

Another one that uses the same event kinds is cypher.space

I haven't looked into plebian.market much, but I believe it is based on the marketplace extension available for LNBits.

As a side note, if you want a lot of feedback from the community on a question you have, it's a good idea to throw in the #AskNostr hashtag.