I'm afraid it's a style that took me years to understand - sometimes described as an early 19th century Paris thing. I'm not about to go backwards. My style does not rely on skeletal support, difficult as that may make it.
The tiny movement you need comes from the knuckle bridge with the slight "pressure" felt as not going towards the finger, but to the outside of the palm .... Preferably no deliberate movements in the other joints...In that case, you are surely making life more difficult for yourself than it could be. You can't walk on a balance beam before you learn to find balance on the floor, you know.
You would seem to have a single model of piano playing in your head and are consequently mixing chalk with cheese. I don't play from the knuckles, I play from the nail joint. I don't walk, I creep!
You simply have to know where the point of sound is, time your movements accordingly and release immediately when you hear the sound result.
It does in no way depend on any movements of the nail joints,
In my case it does. I initiate the movement by the nail joint.
There are different styles of playing. You play from the knuckle like 95% of players and I play from the nail joint. It's chalk vs cheese!
Be arrogant...
That's rich, coming from the forum's own self-appointed caped crusader! You've cried wolf so many times it's meaningless.
I forgot you just get more vicious if your bluff is called. I'll leave sleeping dogs to lie.
Learn the humility to accept excellent advice...
Sounds like your piano is full of Rockwool