Just an aggregator of on-ramp services, not a real merchant system. Not good for conversion rate or user understanding because it cannot be iFramed and users are confused when sent randomly to a page to buy crypto to an unknown wallet with no info about the purchase. And you are right that crypto on-ramp is less likely to go through than other card purchases; this is mainly due to the MCC
It works if your users are informed in advance what they need to do and not to change anything etc. but unlikely you would have a business where that is true