thank for help and great support Jake lo,
i have downloaded the file and tried to follow to tutorial, hower i already struggle on (Create the USB installer via Terminal with "createinstallmedia"), i assume this has to be done inside a mac, and i dont own any , i googled a bit i found a catalina image, i wanted to use that file into virtualbox to install mac there, then continu with your methode , but it can't boot. ( i also tried to convert to .iso , same , doesnt boot)
do you know any workarround since i don't own a mac ?!