> Edit: I'm reading about "libinput" that it has "palm detection" but it's certainly not my problem with the pseudo "noise." Even when I hold only and just one finger, the mouse cursor "trembles" and "shakes."

libinput also adds better noise filtering, finger position precision, and other improved algorithms. I found it quite an improvement even on my current laptop with a great touchpad, and on another laptop it made the difference between usable and unusable.