Thanks for your reply and preventing me to go any further in the wrong direction.
I've made it absolutely clear from the very start of the thread (see email subject lines) that I'd like to install coreboot with OpenBIOS.
With the link https://doc.coreboot.org/tutorial/part1.html I've obviously been led in the wrong direction.
What should I do now (delete the current installation which I made, yet?) if I'd like to use OpenBIOS and where do I find a tutorial or guide that really applies to what I intend to do?