I thought that seed appearance is controlled only by the mother plant, but then started reading about xenia effects, where the pollen can influence the seed coat. So I suppose the larger seeds could be from an interspecies crossing. Pretty wild that there can be such a size difference in the same fruit. I’m appreciating more and more the special abilities of plants.
I think the question is if the changes are perceptible. Corn is quite a outlier in terms of outside seeds appearances, but even with corn not always outside is affected in crosspollination. Some genes are dominant and thus some cobs are uniform dispite definetely being crosspollinated. Same must apply even more different species where outside expression is more limited. I don’t have much experience about interspecific crosses in squash, and those that I (likely) got accidentally had only few percent viable looking seeds. That might be more telling about interspecies cross than looks.
I did have one maxima that likely isn’t interspecific cross but just normally crosspollinated within diverse maxima mix. That one had really big variation in seed sizes. Biggest were bigger than anything I have grown and smaller about half the size. And everything between, but on average big seeds. Discarded some definetely empty seeds, but otherwise they looked normal. The smaller ones weren’t disformed like sometimes is with squash seeds. I suppose there have been some variation before, but this was the first time it was really noticeable. Usually they are more or less so similar that trying to make out differences is pointless. Smaller differences might occur in development anyway. I wonder if it is something how that big seed trait is inherited. That wasn’t even big fruit, just medium smallish fruit with unusually big seeds for the size.