What Can I Sell At Shop Counter

[RasaNova]

I'm not clear on how the player-built shop counter works. From doing a bit of research, I understand that we can't just put every looted or crafted item in a shop counter, only trade goods. But what exactly are trade goods? Is there a resource somewhere that lists what counts as valid shop items, or a way to tell if something can be sold that way?

Also, how does the actual transaction work? Are we alerted when we've sold something? And where does the money go, do we need to collect it somehow or is it magically added to our total?

[Hatsune Neko Gaming]

trade goods only
no weapons or armours.
a amount bought will float above the NPCs head for a few seconds.

[Shidan]

Each NPC that can buy from a shopping counter has their own shopping list of things they might want, the most common thing being food and drugs/booze. I've got a list of the NPCs and their lists on the wiki, should be up to date. https://kenshi.fandom.com/wiki/NPC_Shopping_Behavior

There isn't much of a notification that something was sold, the amount of money will appear over the NPC's head and then they will leave. The money goes right into your cash, no need for you to do anything to claim it.

[Gopblin]

There is a mod called "NPC enjoy more shopping" or something that gives NPCs more money and most NPCs will buy weapons/armor. As a matter of fact, I believe there are a couple mods that expand NPC shopping behavior