I see, so I could just go to a structure and test to see if I can dock and then see if it has market capabilities? Would I see items being sold at a structure if it wouldn’t allow me to dock there?
If the structure has a market with anything for sale the stuff will show up in the market browser when you’re in the same region. You can see anything listed in Tranquility Trading Tower (the Keepstar in Perimeter) while you’re sat in Jita 4-4 for example.
There are a few structures with markets worth paying attention to. Look for IChooseYou or Tranquility Trading Tower in the name. Either in a trade hub system or one jump out.
Your trade hubs being Jita for Caldari, Hek and I guess Rens for Minmatar, Dodixie for Gallente, and Amarr for Amarr.
It’s more likely that you’ll be “allowed” to move your goods to low/null, only for them to not actually give you docking permissions, kill your ship and take the loot it drops for free.
If you want to trade in low / null, join the alliance / corporation that owns that space.
Why would any group setup and hold territory only to allow you to profit while not bleeding with them for the opportunity, seems like a leach thing to try and do.
Most competent groups have internal logistics and won’t allow a unaffiliated party to profit off them.