I don't know Procreate well enough to answer this conclusively.

But one thing I can say is that using a tablet with a pressure/angle/etc.-sensitive pen and a screen in front of you, is very different from drawing on paper.

Which is very similar, as far as hand/eye coordination and motor memory go, to using a pen with a tablet or a tablet with a built-in screen (e.g. a Wacom Cintiq).

I.e. if you own such a tablet and use it with Krita you may get something very similar to Procreate and call it an alternative.

But if you just own a normal tablet and a screen, learning the hand-eye coordination usually takes six months, from my experience.

That's not really related to the app when you compare desktop painting/image editing apps.

But it matters when it's one of the main features (similarity to pen & paper as far as learning goes).

As is the case with Procreate.

Conceptually yes (and Krita might be more feature rich than Procreate), but Procreate is an iPad only app and Krita is not available on that platform, unfortunately.