What EXACTLY does "pm uninstall" do on an unrooted Android 9.0 device?

There seems to be confusion regarding the behavior of pm uninstall from the ADB shell, see also here and here . **Question:** What configuration files does pm uninstall write to, is it /data/system/packages.xml, /data/system/users/0/package-restrictions.xml or both? Are there any additional files? Note: This questions specifically concerns the behavior of pm uninstall, not pm disable. Furthermore, it concerns the behavior on *unrooted* devices. Motivation: Uninstalling the wrong apps doing pm uninstall can result in a soft-brick/boot loop. Therefore, reversing the effects of pm uninstall can be the easiest way out of such problem, especially if other methods risk wiping data that needs to be rescued.