Hi,
1) Any User can only View the SharePoint Site when click on SharePoint Link .But not able to see any List Present in the Site.
Solution : This is because the SharePoint Site may have the Permission for everyone, where as the list might have broken the permission inheritance from the parent and restricted to certain audience this needs to be altered.
2) Only SharePoint having Owner Access can have the Full Control to view, edit ,delete and read any list.
Solution : Create SP Groups as per naming convention or Modify the existing SP Group Permission Level Such as Members will have Full Control access where as Visitor or Other Group Members just give View access. This will help all the Members can perform the CRUD Operations but Visitors can view the data without any issue.
3) But Any User ,whatever action they are supposed to do in any PowerApps (like Add, Edit, Delete and View)the data, they can able to do .But they can not access any List present under the site (not visible to them).
Solution : Sounds interesting, If you are accessing the data from Power Apps first step we will connect the data-source to the application if the data doesn't have relevant permission the users cannot able to perform any operations to the datasets which you are connected.
For your problem, Lets create a SharePoint Group Named as Power Apps Users in the application and provide the Permission Level as Contribute this will help you address the problem
4) Some List contains more than 30K records.
Solution : This is default item limit in-terms of SharePoint, which allows 5000 item view per page/api call and in PowerApps Max of 2000.
- Index the relevant columns which you are going to use at Max you can index 20 columns per list.
- In Power Apps use delegable queries such as Filter, Starts With, Ends With.
- Use Pagination techniques or lazy loading in the Power-apps gallery for showing the records.
Hope this will helps
