I have a FlexSecure (same form factor as the Apex Flex) in my left wrist / forearm: Flex Location help - #28 by MDT , Install Videos and Pictures 🩸 - #269 by StarGate01 . I had no issues with this placement for well over a year now. Scanning it is okay with a smartphone, for a desktop reader you have to rotate your hand. Coupling performance is okay. Still, I got a large implant in the top of my hand: Install Videos and Pictures 🩸 - #388 by StarGate01 which performs way better in terms of coupling due to the large antenna.
The FlexSecure was inserted with a needle, no stitches, no problems.