I am quite excited by this… the Macbook Pro that is displaying the installer is officially only supported by Big Sur, OpenCore Legacy Patcher has configured a Ventura install. The hardware was bought to provide a donor screen to a more recent Macbook & this is a useful ‘sandbox’ unit for testing, experimenting, and so on.
Given some knowledge of the MacOS directory services I likely could have simply modified group membership, that might come later.
While intermittently cursing MacOS’ obfuscation of something analagous to other *nixes ‘single user mode’, my realisation that recovery mode affords, practically, the same thing has been a useful learning point.