Can I use Savable Data Pages to save multiple instances in a Page List?
Yes. This will likely be easier if the Savable Data Page is itself List-structured.
For example, when gathering the drivers on a car insurance policy and having this Savable List Data Page drive a repeating, editable structure on the UI. This shows the current drivers (retrieved from the Data Page Data Source), captures edits and can then be configured to be saved either at the completion of that Flow Action, or some later point in the Flow.
List Structure Data Pages do not have the "Database save" Save type, which is the reverse of the Lookup Data Source that works with exactly one record. If Pega is the System of Record for the drivers on the policy, an Activity Save Plan would iterate over the list (.pxResults) and issue an Obj-Save for each element in the list.
Another technique, when used with auto-populate Page List properties that utilize the "Load each page in the list individually" option, the Single Page Data Page used to load each item in the list can also be a Data Page that encapsulates how to save each instance back to its source.
Remember, don't ever use Commit in your Save Plan activity as this will commit deferred saves that are unrelated to your Savable Data Page.