Hyde here from Shopify.
Other gateways can be integrated but because that is the list of verified gateways with Shopify, they are the only ones we can support. This is because we cannot guarantee how an external gateway that is unverified through Shopify would work with our platform.
To use a payment gateway that is not on Shopify, you would have to hire a developer to set it up as an external redirect checkout that can use that gateway. Here is a link to our Shopify Experts to assist you if needed.
I hope that helps!
All the best, Hyde.
This list is not very useful.
I asked specifically for gateways that actually accept payments for adult products. Stripe (which is in your list) blocked the activation of my account because of this. I would like to avoid having to check every single one of them, and I'm sure I'm not the first one running into such a problem.