Hi @Anonymous ,
Do you want to send an approval email to the Approver when the Requestor adds item to your SP list?
Do you also want to send a form to the requestor to update their request?
Based on the needs that you mentioned, I think the comnination of PowerApps and Microsoft Flow could achieve your needs. I have made a test on my side, please take a try with the following workaround:
Flow's configuration as below:

Within the "Send an email 3" action of above flow, you could embed the Web Link of your PowerApps app along with a ID parameter into the email body as above. Then the requestor could edit their request through your PowerApps app directly via clicking the web link in their email body.
App's configuration as below:
Set the OnStart property of the App control to following:
Set(ItemID, Param("ID"));
If(
!IsBlank(ItemID),
Navigate(EditScreen1, ScreenTransition.None)
)
Within your Edit screen, set the Item property of the Edit form to following:
If(
!IsBlank(ItemID),
LookUp('YourSPList', ID = Value(ItemID)),
BrowseGallery1.Selected
)
Note: You need to generate an app based on your SP List data source firstly.
More details about editing an record through the embedded link within the email body of an email, please check my response within the following threads:
https://powerusers.microsoft.com/t5/General-Discussion/Embedded-link-to-a-Sharepoint-List-item-in-PowerApp/m-p/303910
https://powerusers.microsoft.com/t5/General-Discussion/Editing-a-record-from-a-flow-powerapp/m-p/265416
Please consider take a try with above solution, check if the issue is solved.
Best regards,