Hey thanks for figuring this out. Hopefully Purism will support this when Crimson launches. I found I did not have to install the Debian package list as you did. Here are my updated steps to do this all from PureOS on the Librem 5.
# Update to PureOS Crimson
$ sudo nano /etc/apt/sources.list
# /etc/apt/sources.list
deb https://repo.pureos.net/pureos crimson main
deb https://repo.pureos.net/pureos crimson-updates main
deb https://repo.pureos.net/pureos crimson-security main
# disable phosh
$ sudo systemctl disable phosh.service
# Install plasma-mobile and greetd that will start plasmamobile
$ sudo apt install plasma-mobile plasma-mobile-tweaks plasma-settings plasma-phonebook plasma-dialer spacebar angelfish okular-mobile greetd
# Generate a greetd "greeter" which is plasmamobile
$ echo '
[terminal]
# The VT to run the greeter on. Can be "next", "current" or a number
# designating the VT.
vt = 7
# The default session, also known as the greeter.
[default_session]
user = "purism"
command = "startplasmamobile"
' | sudo tee /etc/greetd/config.toml
# Enable the greeterd greeter
$ sudo systemctl enable greetd.service
# You should be ready for a restart now
$ sudo reboot
I will update with similar steps on the Debian wiki for Mobian so this is less confusing.
I also ran into an issue where I couldn’t remove phosh as it was tied to a librem5-gnome-core package that was held?