Hello, @AndreBastos !
Karlie here from the Shopify Support Team! Payment gateways are specific to which ever country you’re selling from. You can check out our payment gateway list, here, to see what payment gateways would be available to use from the country you’re currently residing in/selling from.
You had mentioned that you had asked for access to use a custom gateway, can you tell me more about this process? Did you ask for access from Shopify or from the payment gateway?
Looking forward to hearing back from you!