Preventing users accessing the SharePoint list that a PowerApp is connected to

I'm building a marketing studio time request app that doesn't contain personal information but business sensitive information from the point of view that we don't want people to see other people's submissions due to the internal politics that might result from it.

I am setting up the PowerApp so that staff can submit their time requests and then can go back into the app and view/edit their own submissions only using a formula based on user.  The data source is a SharePoint list.  I understand that in order to add/edit from the PowerApp they need to have the relevant permissions for list in SharePoint.  

So the PowerApp will act as the front end for the submissions and the SharePoint list will act as the back end for the team processing the submissions.

I don't want people in the organisation to be able to access the SharePoint list and view other people's submissions/list items or have the ability to edit other people's submissions/list items.

I could hide the SharePoint list as much as I can by not having it on navigations etc and even create a default view that contains bare minimum info in case someone does navigate there but I feel it's still open to being discovered and information viewed.  This is a worry for any future apps that I might create that contain personal data or business sensitive information.

Does anyone have any suggestions about the best way to control this and prevent people from accessing the SharePoint list that the PowerApp is connected to? 

Thanks,

Anna