This is a remix of @Swesen_3047 Nintendo Mount, however, instead of attaching to the wall with screws, this uses a hook to connect to an existing TV mount. I did recreate Swesen's design in Fusion 360 and I've shared step/f3d files.
This works with my Echo Gear TV mount, and I suspect it works with others.
I don't know if it was needed, but for maximum strength I printed the model on its side, and upped the wall count to 4. To avoid supports you can split the model in two, and use Prusa Slicer's connector feature.
The author remixed this model.
Tweaked the original design to remove screw holes, and add a hook to connect with a french cleat style TV mount.