Hey Sam, no one seems to have answered your question, so I'll have a go based on what has been said on the #community-meetings channel on the B3 discord -

At present, most of the work is proceeding on a private github server.  The reasons for this are as follows:

It should be pretty well known by anyone who has looked into B3 Coin that there are no development funds.  The BCT announcement clearly said at the very beginning the project was “Anti-Instamine, No Pre-mine, No ICO, No IPO” …. That means no funds for the team behind the coin and no development funds.  The only attempt to rectify that was by this Team, but was blocked by someone we all thought we could trust … not going to talk about that except to illustrate that even with that major setback – this Team continues to work away at a volunteer’s pace.  This makes us the little guys … the underdog.  How can we compete with a Bitfinex, or another well-funded project?  By keeping our cards close to our chests.  If Kdog pushes code for innovative features to the public Github, what is to keep better funded projects who are going to get their DEX to market before us from saying “oh, nice” and taking that feature into their DEX?  Likewise, saying in the discord that the DEX will have “X”, which will set us apart from the crowd, or releasing screenshots, quite possibly could encourage others to work those features into their product.  It doesn’t make any sense, and honestly, keeping quiet about the development is the only smart move.