typically it is a P**N site, correct me if Im wrong OP.
It's going to be difficult to find anything relaible for your business. However, a good start is to contact some of the major Adult payment processors like CCBILL, Verotel etc. and ask what jurisdictions they support / are allowed. Then checkup on these countries.
For company formation it's typically not difficult but for bank account opening it get's challenging, most setup a cover business to get banking facility for their business.