Hi Oliver,

If I understand correctly, you want to run Zephyr OS on Cypress BLE chips, but do not want to use the fully open source BLE stack in Zephyr OS. You will need to start with adding your SoC and  board support in Zephyr project.

If you just want to use Cypress BLE chip as HCI controller to your host SoC that you want to migrate to Zephyr OS, then Zephyr BLE host stack supports many HCI transports (H4 over SPI/UART/USB), besides you add your host SoC and board support in Zephyr project anyway.

If you provide further details about your board, single chip solution or connectivity solution, we may be of better assistance.

Regards,

Vinayak