This permission setting on SharePoint list will also work for PowerApps. You do not need to add any additional settings. When you share this app with UserA, and he open this app from his PowerApps site, PowerApps will prompt for credential of SharePoint connection. After he logs in with his SharePoint account, app will only show the items that he could access with this list (which are the items that are created by himself).
If you want some users to see all items from PowerApps, then you will have to change the first setting to Read all items in SharePoint site. And then in the app, you could Filter the Gallery with formula like below:
If(User().Email="xxxx" or User().Email="xxxx",ListName,Filter(ListName, Author.Email=User().Email))
Community Support Team _ Mona Li If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Changing the list settings to "Read All Items" is must but is not enough, I checked before writing this post, but yesterday I made some changes in site permission levels and add the approver user "Approve Items " permission - plus also as you advise me for "Read All Items"- so, now users can see all items!
now I can add Filters in PowerApps for specific approvers to see the items per conditions.