Great one!
Glad I can help.
About the trading volume on the Hive DEX, as far as I'm awere, there is no official API endpoint that shows this. But I might be wrong. Maybe some of the frontends, PeakD or Ecency have one. I also know @mahdiyari build a frontedn DEX. So I'm pinging him as well.
Eventualy I can build one if in dire need :) and give it that to Coingecko.
When I built https://hivedex.io I also made proper APIs targeted towards both coingecko and cmc according to their documentations. In order to have the HIVE/HBD volume tracked, they first needed an exchange to be listed. So hivedex.io had to be listed for them to track hive/hbd. I did build all the APIs and they didn't list anything. I remember crimsonclad also following up which resulted in nothing.
I did remove the old APIs I built for them in favor of a more decentralized API which is hosted on both of the following:
https://hafsql-api.mahdiyari.info/#tag/market
https://rpc.mahdiyari.info/hafsql/#tag/market
The above API is a complete market API and should satisfy any listing.