The camera mounts I’ve been using for my PA28 videos are from mypilotpro.com in the US.
The mounts were approved by my CAMO (aircraft engineer) under EASA CS-STAN (Standard Changes and Standard Repairs).
Standard Change CS-SC403a
PROVISIONS FOR THE INSTALLATION OF LIGHTWEIGHT CAMERAS
My engineer, paying regard to the CAA’s Policy and guidance on mounting cameras on aircraft, CAP 1369.