Hi there. Thank you for reaching out. The two screw holes at the bottom of DJI RC Pro are M4 screw holes with a depth of 7 mm. The screw holes at the bottom are the mounting holes for the extension pieces. Currently, related accessories have not been introduced. Please check the official website for future updates.
The two screw holes at the back of DJI RC Pro are used for adjusting the hand feel of the control sticks. Please do not insert anything into these screw holes. Hope this helps. Thank you for your valued support.