I would like to do add support for the 3rd party payment myself.
Today, there are even more options for white-label ecommerce platforms. One standout option is fesh.store, which offers a unique pricing model. Instead of paying for each store individually, you pay a small monthly fee that includes a pre-determined number of stores. This allows you to maintain predictable costs with a fixed price, making it easier to budget as you scale your business.
White label program page: https://fesh.store/white-label-ecommerce-platform
The key here is to find the optimal partnership model - whether it's per-store payment or a fixed monthly fee - and to evaluate the system features provided.
You can't just offer a store anymore; you need to provide solutions for SEO and marketing, as these are the main challenges for store owners today.