Only way i could handle crypto efficiently without passing through clown EMIs is using onshore banks. That of course requires your money to be clean so if you got dubious sources you don't have much gateways to get access to banking unless you're well connected.
There are international banks that will look the other way if you're a private banking client but who will not hesitate to close your account if you are a retail customer and have crypto withdrawals. HSBC, Barclays, etc won't care much about crypto if you use reputable exchanges and can document your wealth properly and if you have a lot of money with them (1m plus).
Only other way as a retailer is to use local banks where you live (I know in some countries that is still difficult anyways since no banks are friendly with crypto), otherwise
cash it out via OTC trades (
Bitcoin for cash type of deals) then slowly deposit the funds in an account.
If you accept crypto as a business and you're in a not-so-friendly jurisdiction when it comes to crypto then you're just shooting yourself in the foot and need to rethink your business strategy or location. If you try too hard to find workarounds and resort to sketchy EMIs to move money you'll create more problems instead of fixing that one issue you initially had.
Mercury Bank is a legit entity, they are more conservative because it's online and there is no in-person
KYC, you'll just need to avoid triggering red flags and have a real business with real cash flow to be able to operate there. Most banks are starting to be very hostile to simplistic business models or randoms showing up saying "they're traders and they need a
bank account". Crypto is going to be treated like forex/derivatives in the sense that if you have a company trading that market, you'll need to show some kind of license for it or at least a proof of regulation. And they'll ask for it even if you don't trade third party funds simply because they don't want people who can just pump millions of undocumented cash into the company, show up to the bank and call it "trading profits" (That trick is getting old and banks have caught up to it, they simply won't trust your word.).