Stop users from show/hide columns or create more views

I have a SharePoint site with Owner permission.

I want users to be able to add/view/edit/delete record through PowerApps and not directly through SharePoint interface.

• I have given users EDIT and CONTRIBUTE permission: The PowerApps side is working perfectly
• I have hidden Lists from Site Contents: This is working OK for users who don't know the URL
• I have created only one view - All Items and I have hidden columns

However, this is not preventing other users to come to SharePoint (if they know URL to List) and then using Show/Hide option to display the data columns, save the View and exporting everything to Excel. Is there a way to prevent this, or make it harder?

I know how I can modify what EDIT and CONTRIBUTE permission allow to the user. But I am not sure exactly what to change, and if this is the correct approach.