itch.io

Overdoll (https://overdoll.com/creators) (Help Page: https://overdoll.com/help) seems promising for digital artists, and I assume it could work for game creators as well, but it is currently invite-only, so I'm not sure it's quite ready for widespread adoption just yet. You could give it a try though and see if they allow you onto the platform? Their ToS and Community Guidelines both seem pretty reasonable and accepting. They apparently use Paxum (https://www.paxum.com/) for payment processing.

If it fully opens its doors someday to public registration, it may be a very viable option in the future, as there are no upfront costs for creators to use their platform, and they only take a fee of sales instead. For now though, it may just be like you mentioned of going with a payment processor that allows adult content, even if they are not as well integrated online.

It's a strange situation really. There needs to be a payment processor that's okay with taking "high risk" adult content related payments and dealing with the high rate of chargebacks etc. but that's also well integrated into various online platforms right next to Paypal, Stripe, and so on, to make it as easy as possible for people to choose it on the more popular sites and services. I'm sure it's all more complicated than I understand though, easier said than done.