There really doesn’t appear to be any room for misinterpretation or negotiation on this one. From the DMA:

(57) If dual roles are used in a manner that prevents alternative service and hardware providers from having access under equal conditions to the same operating system, hardware or software features that are available or used by the gatekeeper in the provision of its own complementary or supporting services or hardware, this could significantly undermine innovation by such alternative providers, as well as choice for end users. The gatekeepers should, therefore, be required to ensure, free of charge, effective interoperability with, and access for the purposes of interoperability to, the same operating system, hardware or software features that are available or used in the provision of its own complementary and supporting services and hardware. Such access can equally be required by software applications related to the relevant services provided together with, or in support of, the core platform service in order to effectively develop and provide functionalities interoperable with those provided by gatekeepers. The aim of the obligations is to allow competing third parties to interconnect through interfaces or similar solutions to the respective features as effectively as the gatekeeper’s own services or hardware.

(7) The gatekeeper shall allow providers of services and providers of hardware, free of charge, effective interoperability with, and access for the purposes of interoperability to, the same hardware and software features accessed or controlled via the operating system or virtual assistant listed in the designation decision pursuant to Article 3(9) as are available to services or hardware provided by the gatekeeper. Furthermore, the gatekeeper shall allow business users and alternative providers of services provided together with, or in support of, core platform services, free of charge, effective interoperability with, and access for the purposes of interoperability to, the same operating system, hardware or software features, regardless of whether those features are part of the operating system, as are available to, or used by, that gatekeeper when providing such services.

This is black and white. Access must be free of charge. There are provisions for necessary limitations to access based on security risks, but there are no provisions for charging a fee for access.