Of course, you could have a more complex engine control scheme, so that instead of % N1 you were actually seeing "thrust %".
Isn't this exactly the system Airbus came up with for the A380? Called ACUTE - "Airbus Cockpit Universal Thrust Emulator".
I only fly the dinky Airbuses so have no idea if it made it onto the production aircraft, but the briefing guide states that
"THR will replace N1 (or EPR/TPR) as cockpit thrust control, [with] 100% THR = maximum available thrust in actual flight conditions without air bleed."