If life started on another planet, then how did it start on that other planet? For sure life could have been carried on that other planet from yet somewhere els

If life started on another planet, then how did it start on that other planet? For sure life could have been carried on that other planet from yet somewhere else, but it can't be comets all the way down! At some point, life must have started abiogenetically somewhere. But if life could start somewhere from non-life, then why do we need panspermia to explain the presence of life on Earth? Isn't it enough to say that life started on Earth from non-life, as it would have to start someplace anyway? Perhaps there's a less strong position that could be supported? Maybe life did start on Earth abiogenetically, but it was enhanced or enriched with life from outside the Earth? But then, how can we refute that? Is there a "smoking gun" that strongly contradicts the default assumption that life on Earth started on Earth? Well I'm asking because I don't know those things (I'm lucky that I only have to study non-living systems). I'm grateful for any knowledgeable answers. I totally agree about octopi, though: they clearly are space aliens.