For a world-class athlete, knowing of a slight power inbalance may lead to an incremental improvement.
Even for a beginner, if they can distinguish power between sides and work on keeping it even, why not ?
This is the oft quoted "benefit" to the pedal based PM but I'm curious why you think it would be a benefit to know the difference between left/right power.
I cannot assert that it would
be a benefit. I can only speculate that it may
be a benefit.
But if an imbalance were noted, the first question would be "why ?".
If there is a real muscular difference, then it seems
like strengthening the weaker side would be in order. Maybe it would work, maybe not. But you can't even get the answer to that unless you have some data that tells you what's going on.
Another thing that occurs to me is that most humans are "side dominant", such as right-handedness. Maybe there is nothing holding back the weaker side except the recognition thatb it is not working at full power. In other words, if you know your left side is lazy, you could coax more out of it just by concentrating on it.
Having both legs do equal amounts of work won't improve aerobic efficiency
Why bother to even buy two shoes and two pedals then ?
Save weight and pedal with one leg!