Ubuntu 20.04 LTS Server Planning A New Means For Automated Installations
Traditionally Ubuntu Server has supported automated installations in the same manner of Debian as they had been relying upon the text-based Debian Installer and thus allowed using pre-seeds. But since Ubuntu 18.04 LTS when they rolled out their new text-based installer for Ubuntu Server that isn't based on the long-standing Debian Installer, they lost the pre-seed support.
Rather than trying to support pre-seeds as in the same format as the Debian Installer, they are working on a new approach they hope to have ready by Ubuntu Server 20.04 LTS. Their proposed approach is using YAML as the format for specifying the server installation data and makes different assumptions about what to do in the case of missing data and other behavior.
Canonical doesn't actually have this new automated install functionality implemented at this stage, at least not in full. However, they are soliciting feedback as to their planned approach as detailed on this Wiki page. They are looking for both the pros and the cons to this planned implementation before going ahead with its design. At this point it doesn't appear they plan to offer any Ubiquity integration for offering the same options (YAML input) via their desktop installer.
It's certainly going to be busy for Canonical developers with the many desktop and server efforts in flux ahead of the Ubuntu 20.04 Long-Term Support release due out next April. This automated server install functionality might also get back-ported to Subiquity on Ubuntu 18.04.x LTS as well considering the functionality is missing there albeit important to many enterprises, particularly those doing mass server deployments.