On Nookazon, the key was to sell whatever rare thing one had for as much as possible in order to be able to buy the overpriced stuff one wanted. It's definitely a sort of luxury market that is driven by people who have boatloads of bells and NMT. I remember one time I was trying to buy something basic from some guy, like wood, and someone outbid me by offering him 1 million bells. For wood! He wrote to tell me he was sorry, but the other offer was too good to refuse, lol.
And one time I listed a crescent moon chair for auction and a lady offered me 2 million bells for it. And she left me a bunch of gifts. It was pretty wild.
Whenever I needed NMT or Bells, I would just list a crescent moon chair. Or Frozen set items. I made good money selling one dude a bunch of orange Frozen items for his "hell frozen over" horror island.
There are definitely some nice people on there. One seller, with a very fancy island and house, crafted some items for me for free when I went to do a trade for something else. And there were others. But there are scammers and clueless folks as well.
Nooks Cranny on here is better, once you learn how the donate TBT function works and such. It's more laid back with much lower prices. Nookazon can be fun when you want to fire off a bunch of trades at a fast pace with strangers. It's more gamified like when you sell your spare Valiant statue for 80 NMT and woo hoo, you can go on a shopping spree. I haven't had the energy to trade on there in months though.