The new V4.4 Popsell APIs are currently evolving, and the API reference is also being updated.
New API Reference 4.4 will be released in Q1 2022.
API references provided below are Beta versions.

Swagger sample (Beta version of the Popsell API reference) : https://petstore.swagger.io/?url=https://maxime.popdev.popsell.com/API_DOC/swagger.json