https://www.erisx.com/product/futures/
We can't really say that it is not popular, Bakkt started slow as well, but the last time I checked they've reach record volumes. Besides there's more hype on Bakkt than ErisX physical bitcoin future contracts offering. But we will have to see what will be the impact on the market.
bakkt was a big deal because it's operated by the ICE, one of the biggest and most trusted exchanges on wall street.
erisX is a new startup launched just last year. like ledgerX---who was the first to bring CFTC-regulated physically settled bitcoin derivatives to market---they could be seen as "the little guy". i'm not sure what to expect from them.