Instrumented tests have shown that it's rare for even world class cycle athletes to contribute positive cranking force pulling up on the pedal. What the best ones do is lift most of the weight of their backside leg off the pedal so the frontside leg doesn't have to lift it.
Olympic Silver and Bronze medalist
Leonard 'Harvey' Nitz was said to be quite good at this - measuring lowish on downforce relative to other world class cyclists but able to turn it almost all into forward progress.
We of course aspire to be smooth, efficient and fluid, but unless you're training with a coach and competing, I wouldn't over think this.
For what it's worth, I'm a big fan of clipping in. Not because you can pull (because while you can pull, I almost never do), but because I find it a lot more comfortable, particularly when spinning.
(In my case, I ride a 'bent, so having my feet attached means I don't have to spend any effort keeping my feet out in front of me on my pedals).