@Wicket - I appreciate your replies.
With that said, I can't think of a way to reduce scope on either of the two issues and still have the Add-On do what it is supposed to do.
Reading from Sheets. Seems like I need the readonly for Sheets to get my data. I can still use their picker to pick the spreadsheet, but to read the data, I'll need sheets readonly.
For your comment on the slides currentonly. I love this idea and I want to implement it so users won't be as nervous about the Add-On...however I cannot think of anyway to put pie shapes with varying angles into a slides presentation with that scope. There is no way to do it with the API, I tried a number of things and researched here and elsewhere. I finally realized I could do it with a public template and was really happy about my idea working...and now I'm realizing that won't work because of openById even though it's not the users.
I think I'll have to appeal to the Google team and see what they say. They told me to post here first and from what I'm seeing there aren't any ways around it. I need to have my app do less for narrower scopes or appeal for my original scope request.