Re: Approve / Reject Button in SharePoint Customize Form using Power Apps
Hi @jaina ,
Do you want to trigger the approval workflows(flow with action like "start and wait for an approval") from the PowerApps side?
If yes, I afraid that there is no way to achieve your needs in PowerApps currently.
Currently, within PowerApps, there is no way or function supported to make a response to the approval request sent using " start and wait for an approval " action in a flow.

If you would like this feature to be added in PowerApps, please vote for below idea on PowerApps Ideas Forum:
https://powerusers.microsoft.com/t5/Power-Apps-Ideas/INTEGRATE-Flow-Approval-Buttons-Approve-Reject-inside-PowerApps/idi-p/332337
Besides, there is a workaround, you can add a column in your list to store the Approval request status value (Approve or Reject), then you can simply change this value through PowerApps.
For example, if there is a Text column called ApproveStatus to keep the result, for Approve button, you can try this(DataCardValue1 is the name of my Title control):
Patch(
Approvallist1,
LookUp(Approvallist1, Title = DataCardValue1.Text),
{
ApproveStatus: "Approve"
}
)


For Reject button, you can try this:
Patch(
Approvallist1,
LookUp(Approvallist1, Title = DataCardValue1.Text),
{
ApproveStatus: "Reject"
}
)
Best regards,
Allen