The technical implementation for this should be pretty darn easy once Calamares 3.2.3 is in the repositories. Reason being, there's a new flag:
* The Calamares application now recognizes the `-X` or `--xdg-config` option, which adds XDG_DATA_DIRS to the places used to find QML and branding directories, and XDG_CONFIG_DIRS to the places used to find the global settings and module configurations. This allows a more fine-grained, and more layered, approach to setting up Calamares configurations (in particular, distros can **add** configuration files and give them priority, instead of **forking** configuration files).
So, we can have our default configuration at somewhere like /etc/xdg/xdg-Lubuntu/calamares which has our normal configuration, but then have another directory which can lay on top of it such as /etc/xdg/xdg-Lubuntu/calamares/oem that overrides the main settings YAML but keeps our configuration values the same.
Here's why this is so darn important; OEM is a prerequisite to Raspberry Pi, because OEM works in two stages, with a reboot in between and only stage one needing the live ISO:
- Copy everything over to the system and configure partitioning as well as packages.
- Set up users, theming, etc.
The Raspberry Pi only has stage two, because the Ubuntu infrastructure creates preinstalled Pi images already for server, we'd just have to leverage that.