There are specs on secondary actions placed on the right of a list item. However, they don't mention dividers, and all examples provided go without dividers.
The main info on the matter is provided in this paragraph:
Secondary actions and info should be placed on the right side of the
title. Secondary actions are always a separate target from the primary
action, as users increasingly expect every icon to trigger an action.
The list spec holds concrete sizes and measurements, but again, no divider mentions.
As for the actual usage:
From the examples you provide, it seems to me that the main reason for providing separators in some places is that Google goes against its own recommendations and shows switches as primary actions on the right in its settings app.
Therefore, it needs another way to differentiate switches as secondary actions (where tapping an item leads to another screen) and switches as primary actions (where tapping an item toggles the switch). And that's the reason for adding in those separators—to show two distinct tap areas when the switch is a secondary action.