Great minds think alike
Try this - turn your key to ON (before start / ignition), but don't start your engine yet.
You should hear the sound coming from your rear seat, which will run for a few seconds then stop. If that is the sound you mean, then yes it is the fuel pump.
Easy solution - put a layer of insulflex over the fuel pump / under the rear seat (you'll see a round hatch in the middle, the fuel pump is under that hatch). By now you should be expert in removing and re-installing your rear seat

It will not remove the sound entirely, but reduce it.
IINM, the fuel pump is especially noisy when it is new.
RE the pedal lock, I dunno how much, it has been in my family for many cars, it's like a family heirloom now

I don't mean that sound. The sound I mean appear after start the engine.