It seems not included in the package_info. You can read the notification state in the /data/system/notification_policy.xml before. But you have to parse the value again using regex, to create a proper map of the notification state for each app. It is possible to parse it and use the notification state as the default value. But require much more task and of course root access (not everyone have it). Maybe it is much faster to maintain the database in Automagic and never change the notification manually again via app info setting anymore.
I have made the flow. This will parse the package_info into {app_name}\n{package_name} format for each element
The reason I use list instead of map, is because app name can have duplicate name. When you create a map with the app name as the key, duplicate name will be replaced. And it also make confusion when selecting 2 choices with the same name "Settings". So I append the package name to differentiate them. Later we can parse out the package name by using regex.
Set App Notification State Loop
After that, the global_notification will contain the selected value from previous run, which will be used as the default value (preselected choices). You can init the value by creating it first with list type, leave it blank.
Pro Tip : Use {app,listformat,comma} as the default value, run it once, it will preselect every app. You can then unselect which app you don't want the notification to be on and OK. Edit again the default value back to {global_notification,listformat,comma}.

- Set App Notification State.jpg (80.98 KiB) Viewed 23755 times
I separate the loop into two part, one for enable and the other for disable. Why? Because using your current method, the most efficient loop must have at least 3 element execution per loop : 1 for the loop check, 1 to split the notification whether to disable/enable, and 1 for the action set notification state itself. If you have 300 apps, this will need 3 x 300 element executions = 900.
Using separated loop, I don't need the expression to split to whether disable/enable, hence only 2 element executions per loop. If I enable 200 and disable 100, this will need (2 x 200) + (2 x 100) = 400 + 200 = 600 only. It is 50% more efficient loop at runtime, even though it use more elements. I can use a much lower AES. In this case, I just use 1000, which should be enough. Because the flow itself takes around 20-30 seconds to finish.
My RN5 SD636, with about 250 apps, the flow finish in 26 seconds when using shortcut and 37 seconds when execute manually with the flow opened. This mean each loop takes around 100 ms, and additional 40 ms overhead if the flow is opened.