I rlly want to know, does anyone know or has anyone done Create for 1.20 ?(NOT 1.20.1)
I've tried many things, but nothing help.
I need some guide / How to make a fork for 1.20 or link / source to it.

No, 1.20 is not supported as 1.20.1 was released shortly after 1.20 by mojang.