Is it possible to configure iOS to notify me when it offloads an app? Or when it's low on space? I hit a couple surprises where things like widgets broke because they were offloaded. Ideally I'd be notified early and with a badge as well to clear out space to avoid this happening.
There is no notification for this. What I would suggest is disabling the automatic offloading feature for you.
Then when you get a low storage warning, you can review the current iOS storage and choose the manual app offloads that make sense at the time when you need space. (Or delete data and / or data and apps if that’s better than offloading just app storage.)