One should be able to create a trigger on a SQL on-Prem server.
And then PowerApps should be able to update the column in the target table without getting any "The requested operation is invalid. Server Response : Microsoft SQL :The target table XXX of the DML statement can not have any enabled triggers if the statement contains an OUTPUT clause without INTO clause."
Any flow workaround won't work because on prem. Or else, just tell me (I wish i were wrong so bad !) 😉