How to accept and withdraw payments with almost no commission?

Question

In-app purchases

Good afternoon. There is a need to deposit and withdraw funds for a web service. But this is not a typical online store. (Something like a trading bot with a personal account).
In fact, there should be a transfer to a legal entity / organization (let's say that the client trusts us. No gray schemes, everything is white.), Not necessarily instantly, but preferably with very minimal commissions.
Question: what are the ways to deposit and withdraw funds to cards/electronic wallets with almost no commissions and simple implementation?

Answer 1

Any existing payment system wants your money.
Option 1:
Make your own payment system, your cards, etc. The problem is that your cards, if they cannot be withdrawn anywhere, are of no use to anyone. That is, you will still have to negotiate with banks so that your cards are accepted at their ATMs, heh ...
Option 2:
Negotiate with banks on individual conditions.
We are just now sawing a similar system - small banks willingly go forward on individual terms.
But for this they had to promise huge turnovers - literally billions.
Option 3:
All transactions are fictitious. They are only inside your system. It costs you 0. Withdraw outside the system - only as a last resort. There, yes, there will be commissions. But if you withdraw only large accumulated amounts, then the commission is small.