Another "Help, migrating from Manjaro" topic

So, currently I am quite fond with what I achieved so far (EOS with pamac, breath, mhwd and ofc the glorious KDE), now I am working on btfs-grub. Because this looks like “Scared of Arch? Take THIS!” - which I very much like. I am doing this on servers and VMs like forever (automatic ZFS snapshots), hence my original motivation, me gusta!
I tried to follow the following guide:

but it a bit outdated - is there a newer version of it? Especially this part does not work:

I did a quick search and stumbled over this here:
Btrfs Assistant 1.0 is coming, testers needed - #12 by dalto?
which is quite different - things are improving and changing fast, what’s not to love with this, but that is not helpfull with learning…