This device does not have a 3.5 mm headphone jack. Nor is it possible to use a USB-C to jack adapter to connect wired headphones, as the device does not support this feature. As for inserting an SD card, the information available does not mention a dedicated or hybrid (SIM/SD) port for an external memory card, which suggests that it is not possible to add an SD card to this model. So we'll have to make do with the 128GB of internal storage space.