How can I implement a custom payment gateway for my store?

[rerf2010rerf]

Hi there!

I want to implement a custom payment gateway for my shopify store as my payment provider doesn't have integration with shopify. Is the implementation of a new payment app as it's described here the only way to do so? https://shopify.dev/docs/apps/payments

The docs have lots of information about becoming a partner, app approving process and publishing it in app store, but I don't want to publish it but implement it for my own store only.