I had a squeak as I pushed hard with my left pedal last night. turned out it was the wheel flexing and rubbing on the brake block on every stroke. I adjusted the tiny allen/allan key to re-centre the calliper and all was well.
also had a squeak on my old bikes pedals. I swapped the pedal and still had the squeak, turned out it was my shoes.
squeaks and rattles are infuriating, I need my bike to be stealthily quiet to help me feel smooth and in control, so I feel your pain.
hope you find it.
*edit* I also had a big click/squeak when I returned to the bike after a 10 week absence, the pedals needed to come off and have the threads greased before replacing. They must have kinda dried out.