Based on “Implementing Role Based Security in Power Apps” by Reza Dorrani

1. Have two SharePoint groups with users in it.
   Group A
   Group D
2. Create an extra list call it ‘SecurityCheck’ with two items in it,
   for each item grant access to one group,
   stop inheriting, remove existing groups and, live Group Admin, and for next item leave Group Member
   
   Add the ‘SecurityCheck’ data connection to the App.
3. On AppStart
   Set(isUserInSPGroup_A, !IsBlank(LookUp(SecurityCheck, Title = “A”)));
   Set(isUserInSPGroup_D, !IsBlank(LookUp(SecurityCheck, Title = “D”)));