Recalibrate level and compass with remote control?

I want to recalibrate the level of the Pixhawk with either a switch, or the control sticks of my remote control. It is done like this in all the cheap quadcopters. For example - pressing both control sticks to the lower right forces a level calibration. Even the Walkera QR350 which uses an APM (sort of), does it. So I believe it must be possible on a Pixhawk. I know it can be done in Mission Planner via a radiolink / USB, but that is not what I require.
Can it be done? How?

Andries, it can’t be done, part of the reason is because calibration currently involves more than just leveling, it also requires setting the flight controller on all six axes/sides to determine accelerometer biases as precisely as possible (as you wrote either via USB or radio link). That said there is some work being done right now by the development team to actually learn biases in flight, if it is successful recalibration would be automatic, so stay tuned.

Not sure about the Accelerometer but the compass can be done from the Tx in 3.4 with full throttle and I believe right rudder.
Should be detailed in the wiki by now.

There are no instructions in the wiki that can be used to start compass calibration with Tx

Is it started, but not through the MP HUD display state, or not through the RGB Led to display the state?

Have you tried calibrating using the Tower-app (there are more apps) on Android (with telemetry-radio using USB-cable)? I think I calibrated one multicopter earlier in the summer. That is “remote”.

Tower 4.0.0 Remote Compass calibration, Live Compass calibration, or on-board Mag calibration?