Camera: Lock exposure separately from focus

Hi, I would like to know if there is any trick to lock exposure separately from focus (in the native Camera app). I need to take several photos within the one composition with different focus points for focus staking purposes.

The exposure lock function is cancelled in all cases when refocusing to another point, so its not usable for shooting a series of photos.

I know most other apps (ProCamera, Moment...) can do this, but the original app is unbeatable in terms of stability and ease of use and I am coming back to shoot only with it.

Tkanks.