[Description]
Subiquity's autoinstall does not provide means to, on an installation where the autoinstall.yaml file is in use, to have another autoinstall.yaml file to be loaded "in flight".
This comes in handy when customized installations of Ubuntu (i.e. tailored ISO installations that _already_ contain an autoinstall.yaml file) want to offer the possibility of user-defined customizations.
As confirmed with members of Foudations team, this is not available in Subiquity right now.
[Workarounds]
The usage of early-commands clauses, to merge the yaml files, could be an alternative to the scenario described here, but it would still be quite "hacky" for a feature.
Let me know if further information is required at this time, to evaluate the inclusion of such mechanism in Subiquity. Thanks!
The solution to be implemented:
1. Dynamically supplied autoinstall is used in preference to iso one
2. Reloading of subiquity uses this same location today. This data shall be saved to a spot under /run
3. /run location is preferred over both the dynamically supplied one and the one at /