This is already exist and does not require a partnership: Instant Cryptocurrency Exchange | Best Rates & Lowest Fees | ChangeNOW
I’m sure, there are other services like this.
P.S. the main disadvantage of all similar services - the huge fee, even this one. We have had Coinpayments provider in the past - they took incredible fee from the customers, so… I do not think there is a good and not greed provider unfortunately…