If you are a PHP developer you can develop your own adapters. If not, then you can add coins that are forks of Bitcoin, Monero, or Turtlecoin at the moment. No ERC-20 or other tokens, besides what is available via the CoinPayments adapter.
It is not possible to use exchanges such as Binance API as wallet backends for the plugin. This is because these APIs do not allow you to manage multiple deposit addresses, and this is needed to differentiate between deposits of different users.
P.S. Apologies for the late reply. I wasn’t notifies about this thread. I will look into this.