Hello guys & gals,
I can happily report my problem is solved and the Laptop is booting now properly. So no issue with the boot or grub configuration was present, despite what I assumed.
What I have noticed and what irritated me is the fact that I used the /proc/config.gz from my SystemRescue CD LiveCD which has full BTRFS support.
However, my current kernel config from genkernel had BTRFS not even set, which is strange.
Apparently the "make oldconfig" after coping over the config removed the BTRFS support. [1, 2]
So what I did is copy the config over from the LiveCD again, DON'T RUN "make oldconfig" and run straight genkernel --btrfs all to rebuild everything.
Voila... it straight up boots.
It was a mistake from me to not check it from the beginning because I was 100% confident if I use the same config, it couldnt possibly be different, right? Wrong!
Anyhow you can never stop learning.
Thanks for your support!
Sources:
1) https://www.funtoo.org/Genkernel_Quick_Start_Tutorial
2) https://www.funtoo.org/Building_a_Kernel_from_Source
Apparently both those articles recommend running "make oldconfig", but for me that was the reason why it wouldn't work.
