Your context already has a input variable ( the user), and also timestamp on the table.
Which means you don't need to compare all records, just use the user GUID.
Since the BU designed with Security together, I don't see option you can avoid that especially you want instance action.
If you consider a user application form which is for applying access, it initialize a work flow.
what will you going to do about it ? The user's UPN or GUID will be initialized during the whole flow, and in the flow you will also consider using Delay.
Simple steps:
1. Once submit, approval flow part initialized.
2. Once approved, initialize variables for example, get user UPN/GUID, etc.
3. Power admin will use that to take some action, for example invoke Azure Automation, create a job and use Runbook ( invoke powershell).
4. once done, you even don't need to check dataverse security tables. Of course you can, from here you need to use Delay, for example 5 min.
5. After step 3, you can step in sharepoint setting directly if you more detail , after step 4.
You either use one flow, or split the flow.
