1) OBARUN-INSTALL
a) The installer wants to install 'Syslinux' package while the 'GRUB package is already installed. This is confusing because I had to check if the GRUB package was correctly installed
b) Configuration > 5 - Edit the list of packages that will be installed: Comment syslinux package does not prevent installer to ask again 'Syslinux' for the installation.
You confuse two differents things, the installation of the package itself and the installation of the mbr by the package. By default, two bootloader packages are installed, so syslinux and grub, but the MBR is not installed yet.That's why the script ask you to install the MBR with syslinux.
First , which template you picked?(minimal, jwm, ...)
1) BOOT:
GRUB was not installed in the mbr ( It could be in the form of a choice )
yes, this is planned to have two kind of menu at the end of the installer to give the choice between syslinux and grub, but i have no time for the moment to implement it. Anyway, you need to chroot the system and install mbr with grub following the Arch wiki
https://wiki.archlinux.org/index.php/GRUB. You have to choice to chroot the system, through the installer script picking the number 10 or with the arch-chroot script coming from Arch (should be installed on your system yet).
2) USER:
No user created
I do not know if it's the reason but there could be a problem with first name composed with a hyphen like mine ( jean-michel )
It shouldn't be a problem, anyway if the script detect something wrong at the user name creation, it warm you and ask you to retry. Have you took the number 8 right after the installation of the packages?
3) SDDM
SDDM doesn't start. No idea what's going on. It's still too confused in my mind to understand how s6 works and what are the commands to use to get the useful information.
If it were possible in the future that together we build a graphic representation of this s6 ecosystem , it would be awesome.
please refer here :
https://wiki.obarun.org/doku.php?id=s6opts
in your case :
# s6opts enable sddm
4) STARTX
"Could not sync environment to dbus"
it seem that you have a partial installation so, remake it and we will see what's happen.