We don't have a forum explorer yet, will come soon after we sorted more crucial stuff. I have a cheat way for you to see what is available, go have a look at this Steem account https://steemit.com/@forums.tokenbb each forum is created as its own post and topics and replies are comments. There should be links back to the tokenbb frontend there too.

I don't recall a forum with your requirement but you are welcome to create one, the freemium one just costs 10 Steem to setup on https://tokenbb.io to prevent spam forum creation. If you want to get fancy with custom domains, themes and tokens you can visit https://shop.buildteam.io/product-category/tokenbb/ for subscription options.